In Doctrine and Covenants 19:15, the Savior says:
"Repent -- repent lest....your sufferings be sore -- how sore you know not, how exquisite you know not, yea how hard to bear you know not."
This warning is so chilling. The only person in the universe that "knows" is Jesus Christ. He suffered all our pains and afflictions and understands the excruciating pain is associated with bearing them.
This is why He is the only one we should listen to! Our friends may say "one drink of alcohol won't matter", but our Bishops, or parents, or prophets teach that one drink WILL matter, and that we need to dispise ALL sin.
I cannot understand all the eternal consequences of sin myself, but I trust the Savior and His words through the scriptures. However, I have so far to go before I am entirely rid of sins and the Savior can help me get there.