About other gods-question for theists

[Lek]

was born of a virgin, God became man, his birth was
foretold by Isaiah seven hundred years before it
happened, Joseph believed it, and we believe it."

So the only way you would believe this is by going back in time and doing a physical examination of Mary, talk to God in person and interview Joseph. I guess the early christians weren't smart to verify that Jesus existed and worked miracles even though they were his contemporaries, before being run out of town by the Jewish leaders and used as torches and lion food under the rule of Nero?