Evangelical Protestants think how you worship doesn’t really matter?
It depends on what you mean by how. The content certainly matters. The manner in which the content is delivered--whether you have a pastor in a suit or wearing blue jeans, for instance--is irrelevant. Faith, not works.
Incidentally, if you're so inclined, our Pastor did a sermon on this very topic not long ago. If you want to hear it from the horse's mouth, so to speak, I'd be happy to send you the link.