When someone starts out an argument, "Constantine was the first Pope .. "<quoted text>
Are you sensible? The CC has a history of abuse from 31ce. The 12 Inquisitions for example. Constantine was the first Pope, a Pagan from Rome. All of the teachings of the CC are from Babylon, 2000 years before Christ. Leave the CC church, find the right way to serve God. If you search, He will find you. I do promise.
It really doesn't matter what point they are trying to make afterwards.
I don't mean to insult you, but Constantine was never a Pope. Anti Catholics can't provide any evidence that Catholicism was different before and after Constantine. However, Catholics can provide evidence that our faith was remarkably similar pre 330 Ad and after.