Verses 23 and 24 set up the conditions of mercy surrounding the atonement for sin. The atonement for sin is requisite precisely because of the laws that are given. These laws apply to all, thus verse 23 specifically mentions that all men are so commanded.
Verse 24 sets up the penalty for disobedience to the commands. These commands must be kept or we cannot be "saved in the kingdom of God" (v.23) , and then we "must be damned" (v. 24). Having just set up the justice of God, Jacob now places the dilemma before us. The just God has spoken, and this is his law. To violate his commandments will damn us.