If by "how the Bible's message has changed over time" you mean changes in the actual text, there hasn't been that much. We have manuscripts from many different time periods showing only relatively minor variation. The more usual skeptical argument, in the case of the NT in particular, is that the stories it contains were circulated as oral traditions for 40 - 70 years before they were written down, so there's no way to know how much the stories changed in that period, especialy as they traveled from Jewish Aramaic speakers to Gentile Greek speakers (Jesus probably spoke Aramaic, but the Gospels [except possibly for Matthew] were originaly written in Greek, so you have one layer of translation before they were ever even written down.) Another skeptical objection to biblical inerrancy is internal inconsistency. For example, the prophet Jeremiah at one point says that pretty much all of the sacrificial laws, etc., which were supposedly given by God, were in fact made up by the Jews themselves, effectively contradicting most of the entire book of Leviticus. A good place to go would be "Rejection of Pascal's Wager" at
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. There's a section on the Bible which goes over a lot of this in great detail.