History repeats itself because people never learn. The Scriptures continue to have relevance because human nature does not change. Thus every generation makes the same mistakes.
It may seem that every generation is worse than the last, but this is only the perception of an individual who has reflected on two or three generations within his own experience. History repeats itself not because people are ignorant but because fundamentally nothing changes.
Thus the Scriptures shall remain the only truth, because the Messiah they prophesied did come.
Christianity will always be under attack. That is why Jesus said, "You will be persecuted because of my name." The fundamental truth about the world and the faith in His Name will never change.
As Christians we should always resist evil and face the same challenges our ancestors faced, because that is the way of the world. The world does not change and His Words do not change.
We must live according to the faith in His Name, as Christians, because He fulfilled the Scriptures and completed His Mission on our behalf.
We should accept the sacrifices of His earthly life for our sake and await His Return.
He died and arose from the dead so we should have hope in His Kingdom, a "kingdom not of this world."