But it does not insult the God of the Bible, so there would be no civil law in an explicitly Christian nation that would apply.
In an explicitly Christian nation, the sphere of the Church is matters of faith. The worst penalty a Church can administer is excommunication. If one is not a member of a Church, then one is not under the Church’s authority, which is only spiritual.
Anyone in an explicitly Christian nation who is not a member of a Church is only subject to civil law.
By that standard, Islam doesn’t insult the God of the Bible either. Allah is Arabic for The God. They regard him as the same God that it’s in the Old and New Testament. They regard Mohammed as a Prophet in the Moses/Jesus vein (obviously not regarding Jesus as divine).