What James is pointing out is that, in God's sight, He is not looking merely at our outward appearance; He is looking at our heart. God judges us by what we do. He says that those of us who are rich in faith are heirs of a kingdom that has been promised. This is a promise – not a fantasy dream of a rich uncle in America, but a factual, evidential promise of the reward we have in the kingdom if we fulfil the royal law according to the Scripture.