Here's the deal.
You can know that God exists by pure reason alone. You've probably heard all the standard proofs before, so I'll spare you for now, but if you want knowledge that he exists, some of those proofs (I won't say all of them) are actually valid and sound.
The thing is, though, knowing that God exists is not enough. It's not even a start.
The goal of the Christian life is to love God with all of your being. All Christian morality flows directly or indirectly from this ultimate source. If you love God, you want to do what he says; if you love God, you want to love the people tht he loves; if you love God, you want to help him out and give him good things to the extent that's possible. If you love God, you want to be together with him. And so on.
The problem is that you can't love what you don't know. And you need to know God personally in order to love him personally.
But God in his essence is totally beyond the reach of man's limited intellect to grasp. So you have an impossible problem. You have to love God, and you have to know God to love him, but you can't know him.
The only way out of the problem would be if God took it upon himself to reveal personal knowledge about himself to Christians. And that's exactly what Christians claim he has actually done.
Jesus Christ is God's self-communication to humans of God's own knowledge of himself. Because Jesus took flesh and built a Church and taught disciples, you and I can observe God himself, and his personal actions, and their effects in history and in our own lives, with our limited and clumsy human senses and minds.
That's why faith in Jesus is central to all Christianity. Jesus makes it possible for man to love God in a personal way.
There's so, so much more to say. But here's the main thing. Ritualistic, cultural Christianity, of the kind you're practicing, will never effect the kind of interior transformation that is the whole goal of the Christian life. Further, as I said before, all Christian morality has its ultimate basis in the pursuit of this interior transformation in Christ. Our morals simply do not make sense unless there really is a heaven, and becoming the kind of person who goes there really is the most important thing in life. So, you may be able to get by on a day to day basis and pass for a decent person and not cause any grave social harms with your ritualistic approach. But, ultimately, if you're consistent and actually follow out the reasoning, you're going to find no objective answer to the question of why you should live as a Christian rather than as something else, if perhaps one day your mind changes as to whatever seems to you to be most beneficial to society.
Really, until you actually believe in the God who is Love and who communicates himself to us through Jesus Christ and his Church, your ideals that you talk about in the OP aren't even going to be the same as Christian ideals.