"Probability of Christianity" is way too vague, so I can't answer that. I'm 50% confident in my philosophical (meta-ethical, decision theoretic, cosmological) theism, 92.5% confident in my phenomenal-belief-in-decisions-relevant-transhumanly-intelligent-entities. My confidence in atheism is some weird mixture of the inverse of those two because those two variants of theism strike me as pretty disjunctive, and either would falsify atheism. These are impression-belief mixtures: not entirely Aumann-adjusted, but a little. My impressions are more confident of theism, but my betting odds are less confident.