I'm an atheist. Was brought up going to church, have a reasonable knowledge of christianity. But I just don't believe.
If you don't believe, you don't believe. It's not like converting from christianity to Catholicism. Where the basic principle is the same - that you believe in God. You can't MAKE yourself believe.
If you want to give it a fair shot I'd make the starting point that you will learn more about the religion and see if it changes your views. But I would ask him to engage in that learning too, however it may take place, so you can discuss things together afterwards- after all, this is HIS religion and if he wants you to convert I would approach it as a shared interest to begin with. He can practice what he's preaching.
As for saying he has broken free of his culture, I hate to point out the obvious, but he clearly hasn't. He has broken free from actively practising, but by the very fact he has asked you to convert, he is clearly still entrenched in the culture.
I hope if you are genuinely really happy together that you find a middle ground, but I do strongly think that if he wants you to go down this path and you find yourself open to exploring it, that he should be taking the journey with you.