Most people are familiar with what Christianity is and the opposite view of atheism. But back in the 17th and 18th centuries a third choice appeared that allowed one to have their cake and eat it too. That third option was deism. Deism allows for God to have created the universe, the Earth, and humans and then like any good absentee father to take off and never really to be heard of again. This allowed for the satisfaction of believing in a God who created it all and the cake eating part of doing whatever you wanted without any divine consequences. Of course the deist misses out on heaven, forgiveness, a caring heavenly Father, and purpose of life to name a few, but what the heck, in exchange for doing whatever one wants without divine accountability.
Even though Deism is a fairly modern invention, James makes it clear that any believer who professes Jesus as Lord must include Him in every facet of life. This is the point of our current passage.