Use "hardheartedness" in a sentence

1. The second complaint is their hardheartedness - are we also hardhearted? Please

2. Canaan was and is, according to the Bible, their hardheartedness

3. Urbino attributed it to the natural hardheartedness of women, which allows the earth to continue revolving around the sun, because at that time he did not know that she always erected a barrier of wrath to hide her fear