Door gods are deities that protect doorways, a common belief in Taoism and folk religion. In the past, people would stick their statues on doors to ward off evil spirits, protect the home, ensure safety, help with work, bring good luck, etc. They are one of the most popular protective deities in folk religion. Taoism inherited this belief and incorporated door gods into the pantheon of gods to be worshipped.
The belief in door gods has a long history. According to the Classic of Mountains and Seas, among the vast plum groves is the Dushuo Mountain, with a large peach tree on it. The branches and trunk snake for 3,000 li, and to the northeast of the peach branches is the Ghost Gate . According to the Classic of Mountains and Seas, among the vast plum trees is the Dushu Mountain, on which there is a large peach tree with branches that stretch for 3,000 li. To the northeast of the peach tree is the Ghost Gate, where 2 divine beings stand guard: one is called Shenti and the other Yulei. They watch over the gate and keep an eye on the evil spirits that harm people. Once they spot one, they use a rope made of reeds to bind the spirit and throw it to the bottom of the mountain to be fed to the tiger. The Yellow Emperor paid them respect and worshipped them every year. He painted pictures of Tu, Yulei and 
pictures of the tiger, and hung reeds. If any evil spirits appeared, the two gods would catch them and feed them to the tiger. Later, the belief in Shentu, Yulei, Huru and Taomu as gods that repel evil spirits was passed down in the Classic of Mountains and Seas. For example, the lost text of Jin Ganbao's Search for the Supernatural says: “Nowadays, it is customary to decorate the New Year's Eve with peach-shaped figures, hang strings of cowrie shells, draw a tiger on the door, and place two lamps on the left and right to imitate the tiger sleeping, to ward off evil.” Peaches are also a plant that has been worshipped for a long time. People believe that peaches bring many children and blessings, and are a symbol of longevity. Therefore, they can ward off disasters, evil spirits and ghosts. The Classic of Arts says: “Peaches are the essence of the five trees, so they suppress evil spirits. The essence of the peach is born in the ghost gate and controls all the ghosts, so nowadays people make peach figures and stick them on the door to suppress evil. This is also the case with the tiger, which is the king of beasts and can “hold back the sharp and devour the ghosts”. “Therefore, if you draw a tiger on the door, the ghosts will not dare to enter.” This belief has been passed down to the present day. On New Year's Eve, people often stick pictures of the two gods and the tiger on the door and hang peach branches or peach figures and reed ropes to drive away ghosts and ward off evil. A slight difference from the past is that in addition to Shentu Yulei, the gods depicted in the paintings also include Zhong Kui, who appeared in the Tang Dynasty, and Qin Qiong and Wei Chigong, who appeared after the Yuan Dynasty. In the old Suzhou area, people worshipped the two marshals Wen Yue and Er, Taoism worshipped the Green Dragon and the Tiger, and some regions worshipped Zhao Yun, Zhao Gongming, Sun Bin and Pang Juan. In some places, door gods are divided into three categories: literary door gods, martial arts door gods and door gods for blessings. Civilian door gods are painted in court dress, such as officials, immortals, the toad-like immortal Liu Hai, the goddess of childbearing, etc., while military door gods are painted in the image of military officials, such as Qin Qiong and Yuchi Gong. The three lucky door gods are the stars of good fortune, wealth and longevity. Although these door gods appeared in different time periods and regions, they are still widely worshipped today. Among them, the most influential are Shentu, Yulei, Zhong Kui, Qin Qiong and Yuchi Gong.
Shentu and Yulei are the earliest door gods in our beliefs, and they are recorded in all Han Dynasty books except for the Shanmei Jing. For example, in the sixth volume of the “Compilation of Weishu” (Compilation of Weishu), “Map of the Heavens and Earth”, it is said: There is a big peach tree on Taodu Mountain, with branches and trunks curving for 3,000 li. There is a golden rooster on the tree, which crows when the sun comes out. Under the tree are two gods, one named Yu and the other Lei, both holding reeds, watching over the unholy ghosts and killing them once they catch them. Ying Shao's “Tongyi” (Volume 8) says that Tu and Lei are two brothers who are naturally able to catch ghosts. They often check under the peach tree on Dushuo Mountain to see if there are any ghosts, and if they find any that are harmful to humans, they catch them and feed them to the tiger. Therefore, the county magistrate often imitated the ancients by carving a peach-shaped man holding a reed dumpling and drawing a tiger on the door on the winter solstice and New Year's Eve. Taoism absorbed this belief. For example, Ge Hong's Pillow Book included Yulei in the Taoist pantheon as one of the Eastern Ghost Emperors. His Book of the Original Ultimate Truths of the Multitude of Immortals also says: “During the New Year's Day, people put two peach-shaped figures next to the door and place cock feathers in the middle of a rope to ward off evil.” Since then, the two gods have been worshipped by the people. For example, in the “Jingchu Suishi Ji” by Liang Zongyan of the Southern Dynasties, it is said: “Using peach wood boards to make doors is called xianmu (sacred wood). Painting the two gods on them, Shentu on the left fan and Yulei on the right fan, the folk call them the door gods.” According to the Sui Dynasty scholar Du Taiqing's “Yu Zhu Bao Dian” (A Treasure Book of Jade Candles), which cites “Kua Tu Di” (A Comprehensive Map), Shen Ti and Yu Lei are door gods under the big peach tree on Taoshan Mountain. Song Dynasty scholar Chen Yuanliang's “Shiji Guangji” (A Comprehensive Record of Seasonal Customs) also has a special entry in Volume 5 entitled “Bian Ti Lei” (Debating Ti and Lei), which says that people often write down the characters for “peach” (tao) and “fortune” (fu) on New Year's Day and engrave Yu Lei and Shen Ti on them. The “Beiping Customs and Superstitions: New Year's Eve” also says: On New Year's Day, the families of the nobility hung up Shentu and Yulei, and the common people inserted zhigeng and bo leaves on the doors. “Folk New Year God Picture Exhibition”: “The so-called Shentu and Yulei are characters in the mythology of the Shanhaijing. ... The meaning of the above-mentioned oldest door gods has not yet been completely forgotten. Nowadays, people still write their names on the doors instead of the more popular portraits of generals.” It can be seen that the belief in the two gods is widespread and deeply rooted in the folk. The general method of worship is as follows: a portrait of the two gods is drawn and posted on the door; a statue of the two gods is carved from peach wood and hung on the door; the names of the two gods are written on a piece of peach wood with a vermilion brush and hung on the door; talismans are drawn on the door. No matter which method is used, people believe that it can be used to drive away evil spirits and ward off evil. As for the image of the two gods, there is a painting in the “Search for Gods from the Three Religions” that shows the portraits of the two gods. The two gods are located under a peach tree, with bare chests and breasts, black beards and mustaches, furrowed eyebrows and hair, horns on their heads, and they are holding peachwood swords and reeds. They look fierce, so it is no wonder that ghosts are afraid of them.
During the Tang Dynasty, Zhong Kui, the demon-hunter, appeared. He not only caught demons, but also ate them. Therefore, people often pasted images of Zhong Kui on their doors on New Year's Eve or the Dragon Boat Festival to ward off evil spirits. Yanjing Suishi Ji (Record of the Seasons in Beijing) by Qing Dynasty writer Fu Cha Dun Chong says: “During the Dragon Boat Festival, shops sell yellow paper printed with the image of Zhong Kui, the Daoist immortal, or the five poisonous creatures, which are said to ward off evil spirits. His image is of a leopard-headed man with a bushy beard, eyes like rings, a hooked nose, ears like bells, wearing a black hat, black shoes, a red robe, holding a sword in his right hand and catching ghosts with his left hand. He looks furious and majestic, with a dignified air. It is said that his ability to catch ghosts and his prestige are much higher than those of Shenti and Yulei. As for his origin, according to the records in the third volume of “Bu Bitan”, the fourth volume of “Tianzhong Ji” and the first fourteen volumes of “Liji Shenxian Tongjian”, Zhong Kui was originally from Zhongnan Mountain in Shaanxi Province. He was exceptionally talented when he was young. During the reign of Emperor Wu of the Tang Dynasty ( 618–627) went to Chang'an to take the military examination, but failed because of his ugly appearance. He was so angry that he died by bumping his head on the steps of the palace. When the Tang Emperor Gaozu heard about this, he specially granted him a red official robe for burial. Later, when the Tang Emperor Xuanzong suffered from a spleen disease, he invited many doctors to save him, but the effect was not good, and everyone in the palace was very anxious. One night after Tang Xuanzong fell asleep, he suddenly dreamed that a little ghost was stealing the palace's belongings and running away along the palace wall. Tang Xuanzong hurriedly shouted to catch it, and he saw a big and handsome man running up to the palace, catching the little ghost and eating it with his eyes. When Xuanzong asked him who he was, he replied, “Zhong Kui, the unsuccessful candidate for the military exam.” After Emperor Xuanzong woke up, he recovered from his illness the next day. He then invited the painter Wu Daozi to paint a portrait of Zhong Kui, which was exactly the same as the one he saw in his dream. Emperor Xuanzong was delighted and hung it above the palace gates as a door god. Later, Taoism absorbed this belief and often regarded Zhong Kui as a judge who exorcises evil and drives away ghosts.
In addition, Zhong Kui is also widely circulated in folk culture, and there are stories about Zhong Kui marrying his sister, Zhong Kui catching ghosts, and Zhong Kui hunting at night.
Qin Qiong and Yuchi Gong are the martial arts door gods. They were worshipped as door gods only after the Yuan Dynasty, but they were indeed Tang Dynasty generals. According to the Ming Dynasty's Zhengtong Daozang's “Sou Shen Ji” and “San Jiao Sou Shen Daquan” and “Lai Dai Shen Xian Tong Jian”, the two door gods are the Tang Dynasty generals Qin Qiong (Qin Shubao) and (Yuchi Gong Yuchi Jingde). Legend has it that Emperor Taizong of the Tang Dynasty was not in good health, and there were evil spirits and demons howling outside the door of his chambers. The six palaces and three halls were in a state of unrest at night. So Taizong told all the ministers about the situation. Qin Shubao reported, “In my life, I have killed people like destroying crops and piled up corpses like gathering ants. I am not afraid of little ghosts! I wish to wait with Jingde, keeping a low profile.” Taizong approved the report and told the two men to stand on both sides of the palace gate at night. Sure enough, the night passed peacefully. After praising the two men, Taizong felt that it was really hard to let the two men guard the palace gates all night, so he ordered the painters to paint portraits of the two men, fully dressed in anger, holding jade axes, and with bows and arrows on their belts, just as usual, and hung them on the two palace gates. From then on, the evil spirits were pacified. It was not until the Yuan Dynasty that people followed this practice and worshiped the two men as door gods. There were similar records before, but none of them mentioned these two people. For example, in the “Maple Window Collection” by an anonymous author from the Southern Song Dynasty, it says: “Before the Jing Kang period, the door gods of many households in Bian Zhong wore tiger helmets, and the door of the royal family was even decorated with pure gold.” In the “Bintui Record” by Zhao Shi of the Song Dynasty, it says: “On New Year's Eve, two generals are used to guard the temple, dressed in armor.” It was not until the Ming and Qing dynasties that the books clearly recorded the names of Qin Qiong and Wei Zhi Gong. For example, in the Qing Dynasty, Gu Lu's “Qing Jia Lu · Door Gods” says: “At night, the door gods are changed. The common painting depicts the likenesses of Qin Shubao and Wei Zhi Gong, printed in color on paper, and pasted by small households.” Li Tiaoyuan's “New Search for Gods: The Gods‘ Examination”: “Nowadays, this custom is still followed. On New Year's Day, people either paint portraits of civil officials, write the characters for ’God‘ and ’Ti Yu Lei' (two gods of the Chinese mythology), or paint portraits of military commanders, believing that when Emperor Taizong of the Tang Dynasty fell ill, he ordered Wei Chi Gong and Qin Qiong to guard the door, and the illness was cured.” According to Zhang Zhenhua and Chang Hua's “Chinese Seasonal Customs and Traditions,” “The history of posting door gods is very long. Different regions have different customs, and different times have different door gods. In Beijing, people usually use the white-faced Qin Shubao and the black-faced Yuchi Jingde. Even today, some households still do this to pray for a peaceful and abundant year.” This shows that the two gods have been worshipped since ancient times and are still worshipped by people today.

 门神是道教和民间共同信仰的守卫门户的神灵，旧时人们都将其神像贴于门上，用以驱邪辟鬼，卫家宅，保平安，助功利，降吉祥等，是民间最受人们欢迎的保护神之一。道教因袭这种信仰，将门神纳入神系，加以祀奉。
门神信仰由来已久，据《山海经》说：在沧茫的大梅之中有一座度朔之山，山上有一颗大桃树，枝干蜿延盘伸三千里，桃枝的东北有一个万鬼出入的鬼门，门有上两个神人，一个叫神蒂，一个叫郁垒，他们把守鬼门，专门监视那些害人的鬼，一旦发现便用芦苇做的绳索把鬼捆起来，扔到山下喂老虎。于是黄帝向他们敬之以礼，岁时祀奉，在门上画荼、郁垒和 
老虎的像，并挂上芦苇绳，若有凶鬼出现二神即抓之喂虎。后来《山海经》这种以神荼、郁垒、虎苇索、桃木为辟鬼之神的信仰被人们承传了下来，如晋干宝《搜神记》佚文曰：“今俗法，每以腊终除夕，饰桃人，垂韦索，画虎于门，左右置二灯，象虎眠，以驱不祥。”这中间，桃亦是人们崇拜久远的植物，人们认为桃多子多福，是长寿的象征，因此能够除灾避邪制鬼驱怪，《典术》云：“桃者，五木之精也，故压伏邪气者也。桃之精生在鬼门，制百鬼，故今作桃人梗著门以压邪，此仙木也。”而老虎为百兽之王，能够“执搏挫锐，噬食鬼魅”，“故画虎于门，鬼不敢入”。这种信仰一直流传至今，除夕之时人们常常在门上贴上画有二神与虎的画，并挂上桃枝或桃人和苇索，以驱鬼辟邪。与过去稍有不同的是，画中神人除了神荼郁垒外，还有唐代出现的钟馗，元代以后出现的秦琼尉迟恭，旧时苏州地区人们崇拜的温岳二元帅，道教崇奉的青龙自虎，一些地区信奉的赵云赵公明孙膑庞涓等。还有的地方将门神分为三类，即文门神、武门神、祈福门神。文门神即画一些身着朝服的文官，如天官、仙童、刘海蟾、送子娘娘等，武门神即武官形象，如秦琼、尉迟恭等，祈福门神即为福、禄、寿三星。这些门神虽出现的时间区域背景不尽相同，但至今都被人们普遍信仰，其中影响最深的要数神荼、郁垒、钟馗、秦琼、尉迟恭了。
神荼、郁垒是们信仰最早的门神，除《山梅经》记载外，汉代诸书皆有记载。如《重修纬书集成》卷六《河图括地象》中即说：桃都山有颗大桃树，枝干盘曲三千里，树上有一只金鸡，太阳出来的时候就叫鸣。树下有二神，一个名叫郁，一个名叫垒，均拿着苇索，看守那些不祥之鬼，一旦捉住便杀之。应劭《风俗通义》卷八则称荼与垒是兄弟二人，生性能够捉鬼，他们常在度朔山上的桃树下，检查百鬼，凡发现有祸害人类的就逮之喂虎。于是县老爷常常在腊冬除夕，刻一个桃人拿着苇茭挂在门上，并在门上画一只虎，这都是仿效古人的做法。道教吸收了这种信仰，如晋葛洪《枕中书》即将郁垒列入道教神谱，称为东方鬼帝之一，其《元始上真众仙记》中亦云：“今人正朝，作两桃人立门旁，以雄鸡毛置索中，盖遣勇也。”此后，二神一直被人们所信仰，如南朝梁宗懔《荆楚岁时记》说：用桃木板做门，叫做仙木，画两位神贴在上面，左扇门上叫神荼，右扇门上叫郁垒，民间称他们为门神。隋朝杜台卿《玉烛宝典》引《括地图》称神蒂、郁垒于桃都山大桃树下，为门神。宋陈元靓《岁时广记》卷五中还专门有《辩蒂垒》一条，称人们常于正旦书桃符，上刻郁垒、神荼。《北平风俗类征·岁考》亦称：元旦贵戚家悬神荼、郁垒，民间插芝梗、柏叶于户。《民间新年神像图画展览会》：“所谓神荼郁垒者，乃《山海经》神话中之人物。……上述最古门神之意，迄今尚未全部遗忘，盖今人仍有书其名于门上者，以代较流行之将军肖象。”可见二神信仰广泛深入民间，祭祀的方法大致为：画二神肖像张贴于门上，用桃木雕刻二神像，挂于门上，用朱砂笔在桃木板上写上二神尊名，挂在门上，并画上道符，不管用哪一种方法，人们都认为可以用来驱鬼辟耶。 至于于二神的形象，《三教源流搜神大全》中有一幅画，画中即有二神的肖像。二神位于桃树下，坦胸露乳，黑髯虬须，眉发耸互，头生两角，手执桃木剑与苇索，一副凶神恶煞的样子，难怪鬼见了都害怕。
唐代，又出现了一位门神钟馗，他不但捉鬼，而且吃鬼，所以人们常在除夕之夜或端午节将钟馗图像贴在门上，用来驱邪辟鬼。清富察敦崇《燕京岁时记》称：“每至端阳，市肆间用尺幅黄纸盖以朱印，或绘天师钟馗之像，或绘五毒符咒之形，悬而售之，都人士争相购买，粘之中门以避崇恶。”其形象是豹头虬髯，目如环，鼻如钩，耳如钟，头戴乌纱帽，脚著黑朝鞋，身穿大红袍，右手执剑，左手捉鬼，怒目而视，一副威风凛凛，正气凛然的模样。据说他捉鬼的本领及威望要比神蒂、郁垒高得多。至于其来历，据《补笔谈》卷三、《天中记》卷四、《历代神仙通鉴》卷一四等书记载，钟馗原来是陕西终南山人，少时即才华出众，唐武德(618—627年)中赴长安参加武举考试，仅因为相貌丑陋没有中举，于是恼羞成怒撞死在殿阶上，唐高祖听说后特别赐给红官袍予以安葬。后来唐玄宗偶患脾病，请了许多医生救牿，效果不佳，宫廷上上下下都很着急。一天晚上唐玄宗睡着后，忽然梦见一小鬼偷窃宫中财物沿着殿墙边逃跑，唐玄宗急忙喊叫捉拿，只见一位相貌魁伟的大丈夫跑上殿来，捉住小鬼，刳目而吃之。玄宗问他是什么人时，他回答说是“武举不中进士钟馗”。唐玄宗醒来后，第二天病就好了，于是请来画匠吴道子将钟馗的像画了下来，所画之像与玄宗梦中所见一模一样，玄宗大悦，将之挂于宫门之上，作为门神。后来道教吸收了这种信仰，常将钟馗视作祛恶逐鬼的判官，于是钟馗便成了道教驱鬼捉鬼的神将。
此外，钟馗在民间亦广为流传，民间流传有钟馗嫁妹、钟馗捉鬼、钟馗夜猎的故事。
秦琼、尉迟恭是门神中的武门神，大约元代以后，才祀之为门神，然二人确为唐人。据明《正统道藏》中的《搜神记》和《三教搜神大全》及《历代神仙通鉴》等记载，二门神为唐代秦琼(秦叔宝)、(尉迟恭尉迟敬德)二将军。相传唐太宗身体不太好，寝宫门外有恶鬼耶魅号叫，六院三宫，夜无宁日。于是太宗将全部情况告诉众大臣，秦叔宝上奏说：“臣平生杀人如摧枯，积尸如聚蚁，何惧小鬼乎！愿同敬德戒装以伺。”太宗准奏，夜晚让二人立于宫门两侧，一夜果然平安无事。太宗嘉奖二人后，觉得整夜让二人守于宫门，实在辛苦，于是命画工画二人像，全装怒发，手执玉斧，腰带鞭练弓箭，一如平时，悬挂在两扇宫门上，从此耶祟得以平息。直到元代人们才沿袭这种做法，奉二人为门神。此前曾有过类似的记载，不过均未说明是此二人，如南宋佚名氏《枫窗小椟》曰：“靖康以前，汴中家户门神多番样，戴虎头盔，而王公之门，至以浑金饰之。”宋赵与时《宾退录》云：“除夕用镇殿将军二人，甲胄装。”直到明清以后，书中记载才明确为秦琼尉迟恭二人，如清顾禄《清嘉录·门神》中云：“夜分易门神。俗画秦叔宝尉迟敬德之像，彩印于纸，小户贴之。”清李调元《新搜神记·神考》：“今世惜相沿，正月元旦，或画文臣，或书神蒂郁垒，或画武将，以为唐太宗寝疾，令尉迟恭秦琼守门，疾连愈。”另据今人张振华常华《中国岁时节令礼俗》记载：“贴门神，历史悠久园地方不同，时代不同贴用的也不同。北京多用白脸儿的秦叔宝和黑脸儿的尉迟敬德。至今仍有住户这样做，以祈人安年丰。”表明二神从受祀岍，至今仍然被人们所祀奉。