Antichrist as defined by +Merriam Webster Dictionary is the Chief enemy of Christ who would reign at the end of time, first mentioned in the epistles of St. John. The idea of a mighty ruler who will appear at the end of time to fight against the forces of good was adapted from Judaism; the Jewish concept in turn had been influenced by Iranian and Babylonian myths of the battle of God and the devil at the end of time.
In the New Testament, the Antichrist is a tempter who works by signs and wonders and seeks divine honors. It was a potent concept in medieval Christianity that received the attention of many commentators including Adso of Montier-en-Der, whose work became the basic medieval treatise on the Antichrist.
An example of being an antichrist is forbidding anyone to marry and commanding his people or workers under him to abstain from eating meat on specific time of the season which they considered a "holy day".
1 Tim 4:1 Now the Spirit speaketh expressly, that in the latter times some will depart from the faith, giving heed to seducing spirits and doctrines of demons;
1 Tim 3:12 Let the deacons be the husbands of one wife, ruling their children, and their own houses well.Though there is a big difference in focus between the married and the unmarried.
1 Cor 7:27 Art thou bound unto a wife? seek not to be loosed. Art thou loosed from a wife? seek not a wife.
1 Cor 7:28 But and if thou marry, thou hast not sinned; and if a virgin marry, she hath not sinned. Nevertheless such shall have trouble in the flesh: but I spare you.1 Cor 7:32 But I would have you without carefulness. He that is unmarried careth for the things that belong to the Lord, how he may please the Lord:1 Cor 7:33 But he that is married careth for the things that are of the world, how he may please his wife.
1 Cor 7:36 But if any man think that he behaveth himself uncomely toward his virgin, if she pass the flower of her age, and need so require, let him do what he will, he sinneth not: let them marry.1 Cor 7:37 Nevertheless he that standeth stedfast in his heart, having no necessity, but hath power over his own will, and hath so decreed in his heart that he will keep his virgin, doeth well.
To make a decree or a law forbidding anyone to marry (removing him from performing his spiritual duty if he opted to marry) is one of the doctrines of demons and therefore it's the antichrist.