What group in england proved the greatest threat to the divine right of kings? dutch puritans catholic clergy aristocrats?

I'd be more likely to say simply "Puritans" than "Dutch Puritans," but it's definitely the Puritans.  The Puritan movement in England intended to purify the English church of anything that felt or seemed Roman Catholic in its essence.  Puritans were severely restricted in England itself by laws governing religion, so many of them left to resettle in the Netherlands (thus "Dutch Puritans") or later also to New England on the other side of the Atlantic.  

The idea of "divine right of kings" was one of those Catholic-seeming tendencies that the Puritan mindset rejected.  Congregationalist Puritans considered the assertion that kings were put on the throne directly by God's ordaining to be a heresy (a false doctrine).

Oh, and aristocrats would not be against divine-right monarchy.  They looked upon their own hereditary positions as aristocrats in a similar way -- that they were God-ordained to be leaders.