Of course, everyone who belongs to a church or a religion, thinks that their church or their religion is the “true” one
Yes, that’s the point of faith in Jesus Christ. Of all the claimants to the truth, only Jesus Christ was pre-announced, fulfilled hundreds of prophecies and proved His claim through miracles witnessed by thousands, while His resurrection from the dead showed his very authority over life and death itself. And the fact that thousands of miracles over the past 2000 years and countless NDEs testifying to the reality of Jesus, heaven, and hell simply prove that the battle for the salvation of souls continues to this very day. Thus when Jesus founded a Church and promised to guide it in truth throughout the ages, we believe it. So yes, heaven and hell are real; demons, wicked beings, spirits of the dark, damned souls, diabolical possession, is as real as the nose on your face; so is true forgiveness of sin through Jesus Christ. The problem is that unrepented sin has terrible spiritual consequences.
Thus when the Church teaches that homosexual activity is an abomination in the eyes of God, it teaches it for your own good, for the salvation of your soul. As Jesus said, “so that your joy may be complete”-John 15:11.
The body is the Temple of the Holy Spirit, and Christ paid a terrible price for our salvation, so you don’t want to desecrate your body with sin and abominations.
As for other religions, do realize that every civilization since the dawn of Man has reasoned a Creator, this is because reason itself demands it. Thus every culture in history from the Egyptians to the the Greeks, the Aztecs, the Phoenicians, to tribes of people living on the most remote islands and jungles on this earth have all formulated their own ideas about who and what God is.
While certain truths about God can be grasped through reason alone, through the study of nature and intellectual deduction, Man is finite, thus He has used his imagination to fill in the gaps about God that are impossible to grasp through reason alone. Thus many religions are filled with all sorts of legends and cultural expressions.
Thus, since man is finite, whereas God is infinite, in order for man to know his Creator, God had to
reveal Himself to Man. This is what is known as Divine Revelation, a revelation that culminated in Jesus Christ, and a salvation history that continues to unfold in God’s Divine Plan, chichi inv=cludes giving you an opportunity to save your soul, or to lose it.