By the 'religions that followed it' you include Islam, not merely the direct derivations of Christianity, leaving Zoroastrianism and Judaism as the only major monotheistic movements, with the majority of the planet either polytheistic or animist? Pity, because while Kim Stanley Robinson's "The years of Rice and Salt" has a split point well after the birth of Christianity, and thus not 'untouched', its improved plague essentially eliminates Christian influences, but Islam is still plays a major rôle. Harry Turtledove created a world where Islam never appeared, but unfortunately (for you, not necessarily for its inhabitants) Christianity was, if anything, even more powerful than in our time line.
I have a feeling I read one novel where Judaism had perfused the Roman Empire, rather than Christianism, but have the feeling this was set in a historical period where said Empire was still dominant in its Western, Rome-based incarnation, berore even the Byzantine split, thus well back in time, rather than the society evolved closer to our present day technology.