It's hard to explain. I don't serve God or go good for a reward or fire insurance.....I just feel like it's what I an suppose to do. No news or evidence can change you, it can only reveal who you truly are.
Christ in you is the hope of glory, it is supposed to take place within or it didn't matter whether it happened without or not
I can appreciate your point of view, because the way of the Spirit is a matter of the heart and we often find ourselves wanting to follow the Law of the Spirit in spite of the desires of the flesh that still work in us. This is the influence that He exerts on us for the work of sanctification. Then we think its all because of who we are just because we're basically good people and ignore His work in us, because that's just who we are.
Also for many people with little fleshly passion it would seem that the way of the Spirit is the way they would tend to go anyway. I can point to any number of unbelievers who love to live good morally upright lives, and morally at least do very little of anything that would contravene the Law.
So you might want to follow God because it seems good to you, and therefore you would make a great Humanist.
But entertain for a minute another experience. In my case I am well aware that the desire of my flesh is selfish - narcissistic and not Loving in the way of Agape. In the flesh I only look for my own advantage and I am all to aware of the shortness of life that I have been given. I am not a goody 2 shoes without the influence of the Lord in my life and His Spirit guiding me. If you meet a good person here it is all down to the Lord.
Furthermore I am surrounded by people who have lived lives of so much (immoral) fun they can't stop talking about it and can't wait to get back into it when they next get ashore. The strong and, in the flesh, attractive temptation to follow suit is before me daily.
So when you present to me the idea of serving a God who may or may not exist and the existence of whom has little or no bearing on my day to day activities who, as Jesus of Nazareth points out "causes his sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous", I think well actually the best way I can serve this ethereal God in the short life that I have is to have as much fun as possible.
After all if I've got it wrong what possible difference does it make? At the end of the day we all die and, if Christ did not rise, we are all dead in our sins anyway. May as well be done for a sheep as a lamb, as they say.