▼4:2The mere fact that a claimed prophet, or a claimed message to a claimed prophet, says that Jesus is the Son of God does not mean that the prophet is true. They may say with words that Jesus is God Incarnate, but then they go on to contradict or undermine His teachings, and so, in effect, they are denying his Incarnation. For if he truly has arrived Incarnate, then why do they undermine his teachings?(Conte)

▼4:2 Every spirit which confesses, etc: Not that the confession of this point of faith alone, is, at all times, and in all cases, sufficient; but that with relation to that time, and for that part of the Christian doctrine, which was then particularly to be confessed, taught, and maintained against the heretics of those days, this was the most proper token, by which the true teachers might be distinguished form the false.(Challoner)