For reasons unfathomable , I found myself thinking about time travel the other day. Whether it has occurred to you or not, time travel is a bit tricky to deal with in a Christian novel. Why? Because whether we're dealing with the past or future, we must take into account God's sovereignty.
When dealing with the future, we must make sure we are taking into account as-yet-unfulfilled Bible prophecy even if our story does not deal with those events.