People can be very religious and yet still die in their sins. They may look very much like children of God and yet still be children of wrath. Many unconverted people have beliefs which are similar to true biblical faith, and yet they do not have true faith. Certain people exhibit religious feelings which have the warmth of spiritual love, but are quite empty of God’s grace. Every grace can be counterfeited, even as jewels can be imitated. As glass gems are wonderfully like the real stones, so imitation graces are marvelously like the work of the Spirit of God. In matters of the soul, a man will need to have all his sense about him, or he will soon deceive his own heart. It is to be feared that many are already mistaken and will never discover their delusion until they open their eyes in the eternal world, where they will indeed face terrible disappointment.
A child dead in sin due to his sinful human nature may be carefully washed by his mother, but this will not make the child a living child of grace. The life of God within the soul creates an infinite difference between the person who has it and the one who does not; the point is to make sure that we have this life.
Spurgeon, “According to Promise”