Ugh, I responded to you yesterday, and somehow it didn’t post, so now I have to retype it. Boo!
Still, I look forward to your answers.
You’re right, I don’t know many people who go to church. Most of my friends are atheists and agnostics, with some pagans thrown in just to make it colorful.

But, when I am saying that I think it would be difficult to be a Catholic and be immoral, I’m not just talking about going to Church. Anybody can punch a timecard and show up somewhere for an hour a week. I’m talking about living the Catholic life to its fullest, embracing Christ’s teachings not just within the walls of a church, but also in the world at large. So, I guess what I’m saying is I think it would be difficult to FULLY embrace Christ’s teachings and be immoral. I guess I simply don’t understand how someone can have strong beliefs about God, Christ Jesus, and His Church, and then leave them at the church door. How strong, really, are their beliefs then? I’m not suggesting that people who believe in God don’t ever lead sinful lives, but what I AM suggesting is that to say you are following God and not at least TRY to treat your neighbors with love and respect would be, at the very least, intellectually dishonest. I think it was CS Lewis who said something like ‘Outside of the blessed sacrament, the holiest thing I will ever see is another human being’. And, for a Catholic, (and in his case an Anglican) that’s a true statement, so I don’t know how you can know that statement as a truth and still intentionally and without remorse treat others shabbily.

So, I guess in your scenario are you saying that by belief in God you mean simply showing up to church for an hour a week and shutting their ears and their minds to the message? Because, no, I don’t really see any value in that.
Now, on to your other scenario…so there would really be one rule which is to treat others as they want to be treated. So, now I’m wondering, how would that play out actually? I will give you some examples.
My dear friend Nicky is addicted to meth and cocaine. Here is how he wants to be treated: He wants me, and his other friends and his family to help support this lifestyle choice of his, first and foremost financially, and, secondly, if financial help is not a possibility, to, at the very least, leave him in peace to get high. This is how he wants to be treated. He has been very explicit in this request. Would I have to comply with such a request if I were living in the alternate world, the one where all people are treated as they want to be treated?
And, what of cases where the wants of two people are in opposition? Cases where, to treat one person as they want to be treated would necessarily prevent me from treating another person as they want to be treated? For example, take my philandering friends, I will take my friend Billy for an example, he has a wife and a girlfriend. His wife wants him to be exclusively with her. His girlfriend wants him to be with her, but not exclusively. She prefers that he be married, it makes her life easier. So, whose wants should he favor in this situation? If the rule is ‘treat others as they want to be treated’, then he must dump the girlfriend in an effort to show proper love and respect to his wife, but then he would necessarily be leaving his girlfriend, who he is actually in love with, and that would certainly NOT be treating his girlfriend as she wants to be treated. What would be the guiding principle in that situation?
What if someone breaks this rule? What if someone does NOT treat someone as they want to be treated? What is the recourse? Is their justice for the slighted individual? Who measures out that justice and on what basis?
And what of those whose standard of how they want to be treated might be under-developed? I am thinking of friends I have who really are perfectly fine with being treated badly by boyfriends. It is the standard by which they live. What if I think they should actually be treated BETTER than they are being treated? And what of those who are still maturing? I am thinking specifically of children here, say, a newly turned 18 year old? I assure you that how I WANTED to be treated when I was 18 would have left me dead in a puddle of my own vomit, and I’m certainly grateful that NO ONE back then treated me how I actually WANTED to be treated, so what of those situations?
And, again, by what force are people treating others as they want to be treated? And, how do people KNOW how others want to be treated? I mean, you don’t always have the opportunity to get into lengthy conversations about what another person deems respectful and not respectful so, or loving and not loving, so what would be my guide in times when I wasn’t sure? Would I simply make an assumption? What would that assumption be based on?