Two levels of belief

When you think about it, it seems there's two levels of trusting and believing God, particularly regarding sin and our proclivity towards idolatry. At the first level, you understand that God has set certain things off limits and he says 'no'. But you still desire it, you're very much tempted, and you struggle and strive to be obedient. You grit your teeth and you desperately want to obey God, but the thing still looks good. It still has a certain power over you. In one sense, you strive to be obedient without really believing. You don't fully trust God, but you know he should be obeyed.

The second level is when you genuinely start to believe and trust. When God says a certain thing is bad, and not what he intended, the thing itself looks tainted. When you truly grasp that God is the great designer, you know that nothing can work outside his design. Everything else leads to death. Opposing God has the stench of a rotting corpse.

In this sense your believing and trusting changes your perceptions and desires. Sin loses it's power as you get closer to God. The way you think really starts to change.

King David's word really start to make sense in Psalm 119:

11  I have stored up your word in my heart,
         that I might not sin against you.
12  Blessed are you, O Lord;
         teach me your statutes!
13  With my lips I declare
         all the rules of your mouth.
14  In the way of your testimonies I delight
         as much as in all riches.
15  I will meditate on your precepts
         and fix my eyes on your ways.
16  I will delight in your statutes;
         I will not forget your word.
...

19  I am a sojourner on the earth;
         hide not your commandments from me!
20  My soul is consumed with longing
         for your rules at all times.
...

34  Give me understanding, that I may keep your law
         and observe it with my whole heart.
35  Lead me in the path of your commandments,
         for I delight in it.
...

77  Let your mercy come to me, that I may live;
         for your law is my delight.
...

92  If your law had not been my delight,
         I would have perished in my affliction.
93  I will never forget your precepts,
         for by them you have given me life.
...

97  Oh how I love your law!
         It is my meditation all the day.
98  Your commandment makes me wiser than my enemies,
         for it is ever with me.
...

174  I long for your salvation, O Lord,
         and your law is my delight.
175  Let my soul live and praise you,
         and let your rules help me.