History does not repeat itself. It can resemble itself, but it never repeats.
Rome was not a predominantly Christian nation until its decline started. Some historians ascribe Rome’s decline to Christianity-—pacifism for example drained the ranks of the Roman army.
Slavery became a major issue as well. Small farmers can never compete with slave owners.
I see major differences: Rome was not built on common law, or a Protestant, bottom up religious tradition, or private property with written titles and deeds, or capitalism, the four pillars of American exceptionalism.
Where I do see a danger is the Roman indecision in Germanic immigration. They couldn’t decide if they wanted to let the Germans in and make them citizens, or build walls and keep them out. So they really did neither effectively. Also, it didn’t help that they had a string of truly insane leaders.
Rome’s decline started long before Christianity had an impact.
But it sure does rhyme.