They are positive incentives to live a good and rewarding life.
Which cannot of themselves become moral obligations in the mind of the honest atheist because he is not beholden to anything but his own will. Stop trying to conflate sensible/useful with moral…unless you’re having second thoughts about there not being a God. It sounds ridiculous.
But why do you think that everyone who didn’t believe in God many thousands of years before Christ felt equally obliged to ‘follow the rules’?
Atheism on the scale you have today is unheard of and today’s atheists are fish born in the sea of religiosity that preceded them. Thousands of years ago they were obeying God (Israel, when they weren’t chasing idols) or their idols (everyone not Israel) and governments, much like today. Their obligation was from their deity and their imperative to obey was from the government enforcing the decrees of said deity, real or imagined. Those whose deities were imagined were following the light of conscience and reason that St. Paul described.
However, and for the last time, because atheism removes the possibility of anything greater than the creature, there is nothing greater to which he can be morally obligated. There is no basis for a universal moral code for atheists. The atheist has no moral argument against eugenics, euthanasia, abortion, slavery, racism, misogyny/misandry, etc. It has arguments for how each individual would like to see society run in a way that best elevates his own interests/alleviates his fears/operates in tandem with his preconceived notions of a “good society” based on upbringing.
The arguments you are bringing to this discussion do not align with a worldview wherein you are an accident of nature, cast adrift in space, hoping to convince those with power greater than you that they shouldn’t take all you have and enslave you or kill you because you wouldn’t like it and using religious teachings to bolster his arguments, not realizing that those religious arguments only bear weight by virtue of the deity believed to have given them and to be undergirding them.
If there is no God, religion is meaningless and all it teaches are lies and the rich man who bribes government officials, pays slave wages to his employees, kidnaps women for his harem and does whatever else he pleases is doing nothing wrong because there is no wrong. It’s just that you don’t like it because you aren’t him, you aren’t going to be him and you once heard this story from religious (Christian) people about how these things you don’t want happening to you are “immoral”. This is the world the atheist can look forward to. Particularly if there is a world without Christianity (which there won’t be, lucky you).