By pro-Christian, I mean sources that have a vested interest in the Christian churches being right. For instance, if you wanted to use a theologian as a source, if that person was or is also an active participant in the religion, then they really need to able to demonstrate evidence of objectivity or detachment. Otherwise, it’s just priests, pastors, etc. talking about how Christianity is right, when they’re already explicitly on the side of Christianity being right. That’s a lotlike someone employed by, and/or a big fan of, a sporting organization can and will give us an unbiased opinion about the history/significant events that directly affected said sporting organization. It can definitely be true, but it’s very unlikely that it is true, because the person providing the info is very likely biased towards thinking the organization that they’re an active part of is right and good. So yeah, if it’s coming from a professional Christian, their info about historical Christianity becomes suspect, because they have a vested interest in things related to Christian faith being right and correct.