Because the Church portrays itself as just a way to educate yourself in niceness, culture, morality and love, or worse an emotional consolation, with a far-fetched supernatural story to back that and a history of excessive rigorism and oppression to contradict that, all that with a request for unjustified self-denial and obedience to clearly crooked authorities.
In face of this obvious failure some get attached to the supernatural and excessive rigorist part, others actually believe our job is just "to spread the niceness" and try to get rid of any absolute truth or discipline.
This is all a pantonime.
The Universe is broke and so are we. This is not an opinion, a 'belief' or a faith. It is a fact. We should be up to prove it.
Jesus Christ did several miracles in His life and finally resurrected. This is not an opinion, a belief or a faith. It is a fact. We should be up to prove it.
He did it to fix both the Universe and us, and transform us into something more than what we are now. This is the promise, this is the faith.
Nobody needs the Church or an intricate supernatural story to be or desire to be a good moral person. Our insistance as Christians that this is what "it is about" is as ridiculous as trying to say that you have to be Christian to see the sky is blue. It is ridiculous because it implies only Christians can be good and you don't even need to look at history to see this is not the case. A good look at your televangelist, guru-monk or crony bishop can tell you that. It's not about morality lads, it is about salvation of our very being, either you are a well-adjusted burgeois family person, an underground punk or a half-crazy old hag. You choose to be moral, or intellectual (or both) because this is the right thing to do, whether you're Christian or not. Christians should acknowledge that as a basic fact of life, like gravity, not as the objective of the Church.
If we start treating facts as facts, then morality informed by these facts will improve.