The theology of contemporary thought says that people are basically good, so when evil comes out in tragic events, they try to look elsewhere for the root problem, like to environmental factors, mental health, or the availability of certain firearms. But as Christians we know that the root of evil is in man, and that no external measures can change the evil that is man. Theology makes all the difference in perspective.
The most we can do as society is check and regulate evil acts, like for instance by accommodating self-defense so that individuals have the tools to protect themselves. The true eradication of evil will not come from changing external factors, but only by the powerful work of God in individual lives, and universally on judgment day.