Binding of Isaac - Wikipedia
The religious beliefs of LVD and CD don't work as a defense. INMO, because they did not state that they did it. By hiding the bodies of the children and fleeing to Hawaii shows that they knew what they did was wrong.
The issue of the insurance money and deaths of TD and CV make it even harder to stay with the "religious beliefs" defense.
This was all about money. And revenge. LVD wanted to "punish" Kaye for getting the insurance money from CV's death benefits. Killing JJ was the cruelest thing she could have done. It was beyond evil.
LVD could have easily dumped JJ with Kay Woodcock. Sent Tylee to live with her brother, or just emancipated her and be done with her. But she wanted the Social Security benefits and Tylee's benefits from Joe Ryan. All about cash.