Commentators explain that God judged Judah more harshly than Israel because of hypocrisy. While Israel's sin was open rebellion ('backsliding'), Judah's was 'treacherous' because their repentance was insincere and feigned. As one scholar notes, this is like the Gospel story where Jesus considered the openly sinful tax collectors as better than the hypocritical Pharisees. God detests a heart that pretends to follow Him while remaining unfaithful.