There have been so many killings lately it not only boggles the mind but leads to serious questions of the sort Job threw at God when he suffered disaster on every front. "What the heck, God? Are you there or what? Because I could use some explanations here." (Generously paraphrased.)
Like Job, we receive no clarifying answer because maybe God can see the causes of evil, but we can't. And we certainly have no control over it. Jesus' death on the cross shows he understands our pain and bewilderment and suffering more than we know ... and that he can use it to bring about victory over evil.
But, that's hard to see from our human standpoint.
So what do we do?
We help directly if we can.
We remember that those victims were received by Jesus at the moment of their death. He has conquered death and they are his sheep. Their lives were cut cruelly short but they are now in the place we all hope to be in the end.
We pray, always. For the souls of the victims, for their families and friends in the midst of shock and grief, and even for human soul who did evil's work. (That last is a hard one, but necessary for my own soul. I don't know how God metes out justice but I know that I'd be terrible at it. So that prayer is necessary for me to be able to trust God with it.)
We live our own lives fully and with confidence in Christ and for Christ. Every ripple for good we make in our own bit of the world helps Jesus enter the world with healing, making lives whole again. And it helps defeat evil.
Saint Michael Archangel,
defend us in battle,
be our protection against the wickedness and snares of the devil;
may God rebuke him, we humbly pray;
and do thou, O Prince of the heavenly host,
by the power of God, cast into hell
Satan and all the evil spirits
who prowl through the world seeking the ruin of souls.