God's view of man: Do we have a problem?

Because that, when they knew God, they glorified him not as God, neither were thankful; but became vain in their imaginations, and their foolish heart was darkened.  Professing themselves to be wise, they became fools, and changed the glory of the uncorruptible God into an image made like to corruptible man, and to birds, and fourfooted beasts, and creeping things.  Romans 1: 21-23 (KJV)

Breaking this down into logic flow:

Precondition:  'they' knew God
If 'they' do not: (glorify God as God) and (be thankful to God)
Instead: ('they' are vain in their imaginations) and ('they' have dark hearts)
Then: 'they' (claim to be wise, but are fools) and (reduce God to the same level as they are or even lower)

How do you see God? 
Why would you 'exalt' or 'glorify' Him? 
Why would you thank Him? 
What has He done for you?

Psalm 119:9

How can a young man keep his way pure?
By keeping it according to Thy (God's) word.  (NASB)

Keeping my way pure... according to God's word.  Unless I know what God's word says, I can do this.  Neither can you.  Get into God's word.

Romans 5:8

But God demonstrates His own love toward us, in that while we were yet sinners, Christ died for us. (NASB)

This passage is one that I do not fully comprehend yet. The book of Romans tries to explain this... we see John 3:16 display and quoted all the time, but I get a feeling that I do not really comprehend the love it took to die for me who have rejected God in my past.