What is the problem of evil, and how compelling is it as an argument for God’s non-existence?

What is the problem of evil, and how compelling is it as an argument for God’s non-existence? 100-150 words, please watch video first! thanks!

 http://replay.uci.edu/media/public/spring2017/PhilIntro9Pt3_-_20170605_154048_11.html