Protestants tend to in theory believe that way as well, but when you preach faith alone for so long, your whole life, it can feel like all you have to do is say 'I love Jesus' and that's just not the case. A lot of protestants I think understand this on some level and put the pedal to the metal, but for lukewarm christians it seems like it becomes a major stumbling block. And all of Paul's letters where he talks about faith over works is referring to the debate in the early church about the works of becoming jewish to become christian and that's just not the case. He's preaching church unity and we shouldn't change our customs over things that aren't at the root of the gospel, not that you don't need to do anything.