The first one is this:
"All Scripture is inspired of God and beneficial for teaching, for reproving, for setting things straight, for disciplining in righteousness, so that the man of God may be fully competent, completely equipped for every good work."-2 Timothy 3:16.
The Bible is the complete inspired word of God for us at this time. Notice that it lacks nothing. With it the man of God my be "fully competent" and "completely equipped." Any other revelation that came after it is not inspired of God.
Notice that the Bible puts a curse on anyone man or angel that comes and adds to what has been given to us in the Holy Scriptures of truth found in the Bible:
"However, even if we or an angel out of heaven were to declare to you as good news something beyond the good news we declared to you, let him be accursed."-Galatians 1:8.
All so-called holy texts that came after the Bible was completed at Revelation have to be inspired teachings of demons, including the Koran, and the Book of Mormon, and other so-called works given by angels:
"However, the inspired word clearly says that in later times some will fall away from the faith, paying attention to misleading inspired statements and teachings of demons"-1 Timothy 4:1
Demons will lie to you about the nature of Jesus. Many will have you believe he is God. Or that God works through unholy religions that profess the name of God (even though they don't use Jehovah's name) but scripture says that Satan transforms himself into an angel of light, and his ministers into ministers of righteousness but their end will be according to their work:
"Satan himself keeps disguising himself as an angel of light. It is therefore nothing extraordinary if his ministers also keep disguising themselves as ministers of righteousness. But their end will be according to their works."-2 Corinthians 11:14, 15.
All the inspired gifts the first century Christians had vanished with them. The only ones who had gifts of the spirit, to prophecy, to have divine revelations, to heal, to speak in tongues, etc. all of them had hands laid on them by one of the 12 apostles or Paul. When the apostles died off the gifts of the spirit died off with them, also divine revelation, and prophecy:
"But if there are gifts of prophecy, they will be done away with; if there are tongues, they will cease."-1 Corinthians 13:8.
But it will be very obvious because again, what the divine spirits teach will be in contradiction to the good news of the Christ found in Holy Scripture, 100% of the time, to fool and mislead many.
"“Not everyone saying to me, ‘Lord, Lord,’ will enter into the Kingdom of the heavens, but only the one doing the will of my Father who is in the heavens will. Many will say to me in that day: ‘Lord, Lord, did we not prophesy in your name, and expel demons in your name, and perform many powerful works in your name?’ And then I will declare to them: ‘I never knew you! Get away from me, you workers of lawlessness!’"-Matthew 7:21-23.