Although the person Paul is addressing has changed,
the argument is still continuing underneath the same thought flow. The
thought-flow being how God is found just, in this particular case, by
the fact that He judges. God’s righteousness, it said in chapter one
was seen in the fact that He judges all unrighteousness.
In the previous chapter, Paul showed God’s progressive judgment of men
who suppress the knowledge of God within them, ultimately reveling in
their own darkness and rejecting the light. This sink into depravity
was so bad, that ultimately these unbelievers would uphold and admire
those who did these wicked things and taught others to do the same.
Mind you, this depraved man is not so bad that he can’t do “good” as if
he’s incapable of it. This depraved man knows that he can do “good” but
won’t! This depraved man is guilty, not because of something outside of
himself but out of his own choosing.