Nope. A sin is a sin. A sin can be thinking something that is a violation of the ten commandments. But you don't have to know it's a sin for it to be one. I don't think many people understand that coveting is a sin...but they're still sinning when they cast covetous eyes on the property of others.

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Poor Spot! He was tired of being thought of as stupid. "I'm gonna join Mensa," he said to myself, "and then I'll be legally permitted to wear the society's insignia--a tattoo of a little map pin pushed into my flesh--and then everyone'll know that I'm not dumb at all!"
Spot Joins Mensa
by James "Kibo" Parry