The first principle by which God judges is that He judges righteously ( Romans 2:2). He judges on the basis of what really exists, not what merely appears to be. For example, one might think that since his immoral thoughts are not observable he is free of guilt. But God looks at the heart. Consequently those who have practiced the same sins as those listed previously, though perhaps not in the same way, should not think they will escape judgment ( Romans 2:3). Rather than acting like judges of the outwardly immoral these people should view themselves as sinners subject to God"s judgment. They should not misinterpret God"s failure to judge them quickly as an indication that they are blameless. They should realize that God is simply giving them time to repent ( Romans 2:4; cf. Jeremiah 18:6-11; 2 Peter 3:9). [source][source][source]
"Repentance plays a surprisingly small part in Paul"s teaching, considering its importance in contemporary Judaism. Probably this is because the coming of Christ had revealed to Paul that acceptance with God requires a stronger action than the word "repentance" often connoted at the time." [1][source]