I definitely think cultural aspects have contributed to some of the underlying causes of the mass shooting phenomenon. I don't think no-fault divorce and evolution are the main boogeyman, but I do think it's worth considering the underlying root causes of these freaks' rampages -- though curing broad, cultural trends (e.g. divorce/secularization/social media radicalization, whatever) are basically impossible ways to solve this problem, imo. I'm not sure what Johnson's point is -- even if we take his suggestion as true, what, we should legislate out no-fault divorce as a way to fix the shootings? Absurd.
The much more obvious problem with a much easier solution (though likely imperfect/incomplete) is the guns, imo.