It's about responsibility. Democrats belive the state has a reponsibility to take care of every aspect of your life, including your protection.
God forbid should you have a gun and be able to protect your own life or that of your family. To the Democrats (the statists), that is the responsibility of the state.
"Silence in the face of evil is itself evil: God will not hold us guiltless. Not to speak is to speak. Not to act is to act."
- Dietrich Bonhoeffer