Who or what is an antichrist?

1 Now the Spirit expressly says that in latter times some will depart from the faith, giving heed to deceiving spirits and doctrines of demons, 1 Timothy 4:1 (NKJV) 

According to the words of our Lord Jesus Christ in John 15 the mark of Christian authenticity is abiding or remaining in Him. This is not simply a continual profession of faith, but a remaining faithful to Christ in our orthodox Christian faith. According to Paul, apostasy is a two-fold action of departing from the faith and giving heed to seducing spirits, and doctrines of devils. The Apostle John called the Christian leaders who do this antichrists. View article →