When we begin to go out in the world, the world is going to try to get us to conform to their beliefs.  But we cannot do that.  That is why during our discussion, we see that we must first look at ourselves to make sure we are secure in God’s principles before we go out to the world.  So that we can stand firm and not compromise.

Old Tolerance
The willingness to put up with, allow, or endure people and ideas with whom we disagree.

New Tolerance
The social commitment to treat all ideas and people as equal right, save for those people who disagree with this view of tolerance.

Paul is telling the people that they need to stop living as the unbelievers.  The unbelievers here are those who are ignorant because they choose to be (not those who do not know of God’s message.)  Because they have given up the sensitivity to righteousness, they give themselves to physical sensitivity and sensuality to fill that gap.  But because it cannot totally satisfy, they lust for more and more. 

17 Now this I say and testify in the Lord, that you must no longer walk as the Gentiles do, in the futility of their minds. (ESV)