Leviticus 20 sounds a whole lot like Leviticus 18. In fact, most of the laws in Leviticus 20 are identical with those of the earlier chapter… with one major exception: the latter chapter includes the penalties associated with each law.
Leviticus 18 says, “Don’t commit adultery” (vs 20).
Leviticus 20 says, “Don’t commit adultery… and if you do, both offenders shall be put to death” (vs 10).
And so on.
Here’s a comparison showing the relationship between the two chapters:
|Lev 18||Improper Relationship||Lev 20||Penalty|
|vs 6||Close relatives|
|vs 8||Stepmom||vs 11||Put to death|
|vs 9||Half-sister||vs 17||Cut off|
|vs 12||Aunt (father’s side)||vs 19||Unspecified|
|vs 13||Aunt (mother’s side)|
|vs 14||Aunt (unrelated by blood)||vs 20||Die childless|
|vs 15||Daughter-in-law||vs 12||Put to death|
|vs 16||Sister-in-law||vs 21||Die childless|
|vs 17||Step-daughter & Step-granddaughter|
|vs 18||Polygamy||vs 14||Death by fire|
|vs 19||Menstruating woman||vs 18||Cut off|
|vs 20||Adultery||vs 10||Put to death|
|vs 21||Offer kids to Molech||vss 1-5|
|vs 22||Homosexuality||vs 13||Put to death|
|vs 23||Bestiality||vss 15-16||Put to death|
As we see, all the sins in Lev 20 are covered in Lev 18, but not all the sins mentioned in Lev 18 find a penalty in Lev 20. This may be 1) because the community was not responsible to enact any penalty upon these sins, or 2) because their penalties are assumed in Lev 20. The second option is preferable, since it is unreasonable to think there would be a death penalty for sleeping with an unrelated aunt but not your own mother.
The sexual offenses in Lev 20 also appear to be organized roughly in order of severity of penalty. Most of the “put to death” penalties are higher up on the list, whereas the list ends with “cut off” and “die childless.” We can’t draw too sharp a distinction between many of these penalties, as there seems to be overlap in many areas.
The bottom line is that God takes sin seriously and the death penalty was enacted for crimes much less severe (in the eyes of our culture) than what our government regulates today.