Dear Teen Logo,
C.S. Lewis was an atheist and used to debate against Christians.
His main argument was that God doesn't exist because the world doesn't make sense - similar to the idea that if God is all-Good and there is evil, then God can't be etc.
But one day he thought to himself, if the world doesn't make sense - then I would never know about it. In other words, to say, "The world doesn't make sense" is to be "making sense" of it.
That actually converted him right then and there.
The point is not that there is evil in the world - we know there is.
But is there a "sense" to evil? I believe there is.
"Love" is not "love" at all if it is forced or imposed. There must be a free will involved to accept or reject love and goodness. If there is not, then there is evil already.
To reject love and goodness and their Source Who is God, is to choose the anti-thesis which is evil.
For God to "remain" good, He must respect that choice.
However, God's Will allows for our choices that we make.
God will respect those choices. But our choices that are evil will never circumvent God's Will for humanity from being realized.
God struggles with us against evil and comes to our assistance with His Grace to fight evil which He will overcome in the final analysis.
Your teacher is being rather nonsensical in saying that evil exists and God created evil.
God did not create evil. He created free will as a function of His Goodness. That we abuse and misuse free will is our doing, not God's.
Yet God will accept us against if we reject evil and fight it.
We respond differently to evil than to goodness (if we are on the side of good) and this also has to do with God.
His argument, nomatter how seemingly intelligent, has gaping moral holes that I personally find philosophically repugnant and even puerile.
If he is against evil, what is he doing about it apart from philosophizing?
Anyway, give him my regards . . .
Alex