Then why have many died BECAUSE they trusted doctors?
Because doctors are fallible.
I had to double check the title of this thread. Science is merely an application of epistemology, that branch of philosophy dealing with knowledge. A basic tool of epistemology is logic,
the art of the non-contradictory identification of truth.
Whether we are talking about scientific truth or moral truth, people can know the truth but still fail to act on it. This is why Paul said he does the evil he does not want to do.
Getting back to the evil of homosexuality; we know it is morally evil. We know the health statistics of practicing homosexuals is worse than the general population. Regarding cancer, be that ratio 2.0 or 1.8 times worse, we can approach a better understanding using science to
quantity bad. Someone pointed out that 90% of those infected with HIV come from Africa. Their behavior is bad. How bad is secondary. We don't praise someone who only murdered 1 person rather than many. For crying out loud!