Everyone who has spiritual faith has an assurance that we are saved by the Lord. That is, we believe that the Lord came into the world to give eternal life to those who believe and live by the principles that he taught, that he regenerates us and fits us for heaven, and that he does this all by himself without our help, out of pure mercy.
Believing what the Word or the theology of the church teaches and not living by it may look like faith, and some may even believe that they are saved by it; but no one is saved by this alone. This is in fact a veneer of faith. It is necessary to describe this veneer of faith at this juncture.
A veneer of faith is when we believe and love the Word and the theology of the church not for the sake of its truth or in order to live by it but for the sake of profit and reputation and for the sake of being considered learned. As a result, when we are devoted to this kind of faith we are not focusing on the Lord or heaven but on ourselves and this world. People who are intensely ambitious and acquisitive in this world are more strongly convinced of the truth of what the church’s theology teaches than people who are not intensely ambitious and acquisitive. This is because for them the church’s theology is nothing but a means to their own ends, and the more they love those ends, the more they love—and trust—the means.
Essentially, though, the fact is that they are caught up in this conviction to the extent that they are on fire with their love for themselves and the world and are speaking and preaching and acting from that fire. At such times they are completely convinced that what they are saying is true. However, when they are not caught up in the fire of those loves they believe very little—some do not believe at all. This shows that a veneer of faith is a faith of the lips and not of the heart, so it is really no faith at all.
from Regeneration, pages 18-19