The different between the Law of God and the laws of nations is that God’s Law perfectly reflects His character. It shows us how much we need God to change us because we can’t meet His standards.
The penalty for blaspheming was death, Leviticus 24:9. Paul had once been a blasphemer but he then came to know and experience God’s mercy, 1 Timothy 1:12-14. To hold up God’s Law shows how great His mercy and love in Christ Jesus is for us and others.