What they seem to do, is equate forgiveness with acceptance. The best thing that Jesus said that summarizes this is when he encountered the adulterous woman at the well, and said, "Your sins are forgiven, go and sin no more". (sorry if this is not an exactly correct quote). And when searching that, I can't believe some people think that means Jesus was indicating it was possible to live a life without sinning! In this case, He was referring to the sin of adultory, and clearly it is possible for a person to stop an obvious, outward sin as that, from continuing.