Christianity

By your logic that the giving of the Torah is something we would rationally expect after establishing the existence of God and therefore it makes sense to believe in it despite the ambiguity of the corresponding evidence. Why doesn't the same logic apply to Christian doctrine where we also expect the Messiah to come (from several sources in the Bible, and even from the Torah itself) and we have a certain level of evidence such as eyewitnesses to confirm the resurrection of Jesus, in addition to his teaching and such, why do you still dismiss it?
In other words, if you were born a Christian, wouldn't you use this exact logic to justify your theology, and if so, on what basis do you still reject it?