Verses 14 and 15 say that, and Jonathan was talking about that last Sunday. We know too that when we pray for a fellow believer to be delivered from his sin and forgiven and brought safely through the struggle with temptation to eternal life, then that is a request which is right down the middle of the fairway of God's will, if I can put it like that. It will be granted. How, is up to God. But our heavenly Father will use our prayers as a part of the whole process of purging sin, purifying our lives and fitting us for heaven.
Believers are to pray for one another.
We are to ask God to grant victory over sin to our brothers and sisters who are stumbling and falling, as we do ourselves. And we can be confident that he will do so. He has promised. So that is how we are to bridge the credibility gap between what our fellow believers are really like, and what they should be like if they are truly redeemed children of God. If so, then here is the antidote.