I dont have a clue what Mormons beleive and really do not care.Have you ever studied with the Mormons? There are some who fully agree with what you are saying and have claimed as you do to be sinless. Are you Mormon?
God is my way and as stated He takes away the sins of this world.
If a Mormon wrote 1 John 3 where He takes away the sins of this world and when you see Him as He is ye shall be like Him which does not include sin, and in Verse 9 if you are born of God it is impossible to be in sin, and they wrote for me to be perfect even as my Father in heaven is perfect, and if they wrote John 17 where He in me and I inhim are one as jesus was one in Him, and they wrote to have the same mind who was in Christ Jesus. Then I suppose that you could say I have studied with them.
To be sinless is not a claim but the reality of God manifest to be His righteouss and walk as He walks in it.
If one is a sinner read 1 John 3:8, it is clear who you follow.