"No person has the right to use someone else's body..."

This here is a main point of contention. There are dozens of others, and that's why debates and political parties exist. Not because one side is ignorant and illogical, but because everyone's preception of the world is different. Some see an unborn fetus' life as more valuable than a woman's desire to not be pregnant for 9 months, and some of us are just going to have to agree to disagree about that. (I didn't mention anything about rape cases or injuries or socioeconomic status; that's because if you include those variables, opinions vary wildly within pro-lifers and pro-choicers).

Anyway, here is why I take issue with what you've said: a fetus isn't a person. A human is not a person unless they are self-aware. Fetuses are not self-aware, so the age-old "is it okay to use someone else's body to live" moral dilemma doesn't really work. So you have to either accept that an unborn baby is a person, in which case killing it would be murder, or accept that it is not a person, in which case its rude hijacking of the mother's body isn't comparable to someone getting their lifeblood leeched.

Moral philosophers much smarter than anyone in this thread have been arguing over this shit for decades, so I don't even know if there's a point to this. There's the ol' "you wouldn't let a stranger survive off your sleeping body for years, would you?" and the "oh, but if it's a baby using someone's body it's not as bad because you can still move around" gag. This stuff's complicated.

TL;DR: Debates are complicated, neither side is stupid, everyone has reasons for viewpoints, and /r/news is a cesspit of intolerance for right-wingers.