Under the assumption that there is only one time line, changing the past is incoherent since it amounts to there being one past prior to t2 in which God has a certain belief at t1, and then Jones does something to make a different past, which requires two pasts prior to t2.

Notice that counterfactual power over the past is not the same thing as changing the past. Under the assumption that there is only one time line, changing the past is incoherent since it amounts to there being one past prior to t2 in which God has a certain belief at t1, and then Jones does something to make a different past. That requires two pasts prior to t2, and that presumably makes no sense. What (CPP) affirms instead is that there is only one actual past, but there would have been a different past if Jones acted differently at t2. (CPP) also does not require the assumption that what Jon...