I think you would benefit from reading what actually happened with Galileo. This tract is a good place to start.
Debate is possible within the church. However, part of being Catholic is having faith and believing that Christ founded one church that binds and looses and the gates of Hell will not prevail against it. It seems to me that, like so many in today's culture, your question stems from the pervasiveness of relativism. Your doubt in the existence of moral facts is not unique. Is not part of the reason we follow a religion is that is provides us with a moral framework that guides us through right and wrong? There is right and there is wrong; those truths transcend religion to the very foundation of reality.
An example. Slavery is wrong. Is it wrong because a religion says it is? Or is it wrong because, at the most basic level, it is wrong to take away the freedom of another?
It sounds like you have questions about contraceptive use. I would encourage you to read Sex au Naturel by Patrick Coffin.