Guys, if you haven't figured it out yet, marriage and contraception are pretty much the two (maybe the only two, but I don't spend much time in RC apologetics land, so maybe there are more) issues that RCs can push in order to say that their church hasn't changed, while the Orthodox Church and other churches have. Granted, that's not true, but what else do they have? "The Orthodox Church allows remarriage, while the RCC keeps the practice given to us by Christ of one man and one woman, and that's it", or "Up until the 1930s (or whenever), all Christian churches agreed that contraception was not in keeping with the faith, but then they all changed...except for the RCC! Yay! See, so we are the unchanged ancient church and they are not."
Okay, farcical reconstructions above, but they are reconstructions of arguments I do remember hearing in my RCC and just post-RCC days, i.e., as recently as a few years ago.