I've been LCMS member since I was confirmed in the 8th grade. I know what the church position is, but I think they take this too far. Biblically speaking God requires repentance, which involves not just forgiveness, but the turning away from sin. It's the same thing as what LCMS says when they ask that you have confessed your sins and are working to avoid sinful actions.
I think most Masons would tell you this is the idea behind the purity of the lambskin; it's not that you are perfect, but that you are trying to live a Godly and faithful life. They don't believe it's the good works alone that get you into heaven, it's that the 'good works' are a manifestation of the turning away from sin.
Maybe I'm seeing this wrong but that's what I think.
Greater love hath no man than this....