Screen doors prevent obnoxious insects from entering your home. You must assertively screen out people who are carriers of the virus of doubt and unbelief.
Boldly protect your ears and life from absorbing talk that does not edify and build.
"But he turned, and said unto Peter, Get thee behind me, Satan: thou art an offence unto me: for thou savourest not the things that be of God, but those that be of men."
"A little leaven leaventh the whole lump."