Now, brothers and sisters, I want to remind you of the gospel I preached to you, which you received and on which you have taken your stand. By this gospel you are saved, if you hold firmly to the word I preached to you. Otherwise, you have believed in vain.
— 1 Corinthians 15:1-2

Most churches contain people who do not yet believe. Some are moving in the direction of belief, and others are simply pretending. Imposters, however, are not to be removed, for that is the Lord's work alone. The Good News about Jesus Christ will save us if we firmly believe and faithfully follow it.
http://www.lehrmangroup.com/verse/