This argument that you make against enlightened self-interest is the same argument that is made against those who believe in a specific God.
Allah, according to some radical Muslims, commands them to kill infidels. And BTW, they can quote chapter and verse as to why they are correct.
If Muslims claim that X is good, Buddhists claim that X is bad, and Christians claim that X is neither, then maybe all religion is just personal preferences and biased "enlightened self-interest".
As a Christian we can never fairly say that there are just two kinds of people: people who believe in the Christian God and everybody else. There are some Christians who claim that Muslims are atheists because they don't believe in a Christian God. This is just plain silliness I hope you'll agree.
So again I repeat, it is a good God that has created a world that largely reflects his wisdom and kindness. It is a wonderful thing that a huge percentage of humanity agrees on a large number of basic moral principles. There is much that can be made of this consensus.
As soon as you start arguing that atheists can believe whatever they will, atheists can argue back that you just happened to choose the religion that validated all your prejudices so how are you any different. They can further annoy you by claiming that the reason you happened to choose a religion identical (or similar) to that of your parents is that your family is genetically predisposed to be Methodists, Lutherans, Catholics, Buddhists, etc.
If that one guanine-cytosine pair on chromosome 14 had just been replaced with an adenine-thymine pair then you might just now be walking into a pizza joint in Haifa with a non-descript backpack.