I recently had a conversation with a pal about the concept of "mortal sin" vs. "venial sin". Apparently, in other faiths sin comes in a hierarchy. My friend asked if we had the same sort of distinctions in the LDS faith. I told him there was no formal code of such, as far as I knew, but that we tend to look at the consequences of the behavior to measure the seriousness. There are sins that would get you scolded, sins that would get you lectured by the Bishop, sins that would cause you to lose a temple recommend, and sins that could get you disfellowshipped or excommunicated.
But after thinking about it a while, I decided that was not such a good answer. I used to think that the line in the sand for me was the temple recommend interview.... If I did anything that would violate my worthiness to enter the House of the Lord, I would consider that a "Big sin" where as other indiscretions (taking the Lord's name in vain, or stopping at the store for milk on the Sabbath, for example) I I would consider less serious.
Now I'm ready to rethink that position. Granted, I don't go running to make an appt with the Bishop if I shop on the sabbath (very rare at my house, but it DOES happen) or use the Lord's name in vain. But I DO KNOW these are significant areas of concern for the Lord.
So why do I consider them more trivial than breaking the word of wisdom or failing to pay an honest tithe?
How do YOU decide what is SERIOUS and what is TRIVIAL?