Everyone knew Christ was the Messiah, people just rejected them. He literally raised people from the dead, including himself.
Pharisees and Saducees felt abandoned by God when Christ opened the covenant to all nations, that is, they felt that God turned away from them so it was their turn to turn away from God.
They ought to have done a deal with the Devil. Wheter in person or not, it does not matter.
Albeit atheists say they base their position on le facts and le logic they clearly don't. So arguing with them about the nature of Logos and Ethics or about the historicity of the Bible will get you nowhere. You might convince a few people in the crowd, but it's because recruiting is easier than converting.
How you "convince" an atheist is by destroying the fundamentals of his beliefs. One the validation of claiming he has no emotions only le facts and le logic. How you do that is by mocking his assumptions, materialism and nominalism have no backing of Logos and neither can they provide any real backing of Absolute Truth. Don't let them trick you as they trick themselves.
They want to have this logical system that does not ask any questions about Logics itself, say this to them.
By comparing their position with pagan sects they find silly, I have found great success. Evolution is totemism, the green movement is Gaia worship, the Big Bang is hellenic uncreated matter, etc.
Another fundamental pillar is the validation of having the culturally popular opinion, how you destroy this is by going all-out culture war. It's very simple, and it's a very masculine thing to do. Few words and very forceful, as you push your worldview as the mainstream and the acceptable one. Call them old-fashioned and an useful idiot, as they are.