Fifty years ago, in somewhat more moral days, when even as unbelievers we would have believed in the Christian ethic and would have sought to comply with some better standard of morality, there were many people who prided themselves on living good lives. I have known many such, in my own family as well in years gone by. They were hostile to God perhaps, and they were not believers, but they paid their debts on time, they were scrupulous in their dealings with people. Most of the time at any rate, they were seemingly very honest and upright people and rather proud of it too, perhaps. But God reads the heart. Why were they like that? Well, it was comfortable for them to live moral lives. People do not realise this today, but even aside from grace there is great emotional and mental peace in morality and straightforwardness and honesty. Nevertheless, these people, they lived it for themselves, and if you were to read them at the level of inner, secret motives, you would see very selfish people, very proud people, very self-righteous people. That is the level at which God looks.
Somebody may be involved in Christian service, may be a true Christian, yet doing it for show, doing it in a flamboyant way, doing things to be seen, not out of love for God, not for the love of souls. Even that can happen. God reads the heart. The motives, the desires, the level at which we get satisfaction and things like that. So it is just a warning to us. God reads in a much more profound way than we do and we must take that seriously.