"Ex Nihilo" is the belief that God created the world out of nothing. The "Problem of Evil" is an argument against God existing: it is impossible for a Good Creator of the world to exist because the world has so much evil in it. This Problem of Evil argument depends on God creating the world out of nothing and thus intentionally bringing forth evil.
But the Problem of Evil's premise of Ex Nihilo is totally and completely wrong:
God created (past tense) the universe out of chaos? Consider all the great religious teachers throughout history, Buddha, Muhammad, Jesus, more recently Martin Luther King Jr., Joseph Smith Jr., Pope Francis, etc. What is the one thing they all ask us to do in the name of God? Be better people than we are NOW. IF God has spoken through ANY of these leaders, God is using this world as a tool to help make us better people. Therefore God is creating (present tense) the universe out of chaos.
As evil (chaos) preceded good (creation,) when one of God's creatures exercises free will to chose evil over good, that's not God's fault. Evil was already there, and bringing forth creatures with free will into the universe IS more opportunity for creatures to choose good and thus become good. Creating creatures with free will is a risk God takes in order to make the universe a better place.
Some have wondered if evil is the shadow or absence of good, or does evil have it's own agenda? I say it is both: the status quo of the Universe and our world is dark and chaotic (as Earnest Becker said "...red in tooth and claw, destroying all she creates...") and that the only significant justice and mercy that comes to the Universe that we know of is established by humanity (literally through humans.) God is literally using his children to make the world a better place. Evil is the default state of the universe, and good is thus the shadow or absence of evil.
But I mean shadow here in a most sinister sense: a predator stalking it's prey. Good consumes evil: bad situations are a creative opportunity to create better situations. Evil can cry and squirm and tell nasty stories about good, and though much evil may eventually escape good's hunt, evil's protest will not keep good from having it's feasts. The universe is a massive lemon grove with no delicious fruit, but God & friends are lemon-aid enthusiasts.
