What if a Christian practice isn't found in the Bible?

Les teaches that Satan can transform himself into an angel of light and make it appear he is promoting the Scriptures, leading millions astray. Therefore the Lord has given the Holy Spirit, a mind, and intelligence so that by searching the Scriptures believers can sort these things out. When people realize that something they thought was part of the Christian experience is not according to the Book, the right test is not to demand a verse that says a practice is wrong. Instead, ask whether any verse instructs people to do it. If it cannot be found and is not in the Book, it must be wrong, since anything that is part and parcel of the Christian walk is in the Book. If it is not in the Book, you are on thin ice. Les stresses it is just as important to know what is not in the Book as what is in it, because many think a thing is in the Book only because they heard it somewhere, but that is not the way to go.