As it pertains to the topic matter, God can and does create things that are against Him, on purpose
In fact, if we think about it, every created thing is less than Perfect
God created a perfect devil. Does that make the devil the same Perfect as God? Nope
IF we say God is not in control of everything, that is a far worse slippery slope. A God who ain't so much of a God
The response to this is people will now look at creation, the world around us, and the evil that exists and derive God's nature and will from their darkened perceptions. God is evil. He would have to be. Alas, Jesus came to show us the Father, and He is the exact and perfect revelation of the Father. When did Jesus ever do evil? Scripture says that Jesus went about doing God precisely because God was with Him. So again, where is the evil in what Jesus did? There was none. James detailed the true revelation of God:
James 1:16-17 KJV
16
Do not err, my beloved brethren.
17 Every good gift and every perfect gift is from above, and cometh down from the Father of lights,
with whom is no variableness, neither shadow of turning.
Then, some will redefine what the words "good" and "love" mean. If God is "good" and "Love," but God does evil and hate, then there must be different definitions for these words. They must include what we would consider evil, hate, and bad. And so, if there is a slippery slope, it is one that leads us to a God who is worse than the devil—an all-powerful devil.
Isaiah picks up on the subject in Is 55:
Isaiah 55:8-9 KJV
8 For my thoughts are not your thoughts, neither are your ways my ways, saith the LORD.
9 For as the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts.
Now, some will take these verses and take them to mean that God's ways could include what we might consider evil ways and His thoughts include what we might consider evil thoughts. They reason that God is beyond our comprehension and so we actually cannot reason what He might do in any situation. Yes a causal reading of the verses that follow paint a completely different and opposite picture. This is how God's ways and thoughts differ from ours:
Isaiah 55:10-13 KJV
10 For as the rain cometh down, and the snow from heaven, and returneth not thither, but watereth the earth, and
maketh it bring forth and bud, that it may give seed to the sower, and bread to the eater:
11 So shall my word be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I please, and it shall prosper in the thing whereto I sent it.
12 For
ye shall go out with joy, and be
led forth with peace: the
mountains and the hills shall break forth before you into singing, and all
the trees of the field shall clap their hands.
13
Instead of the thorn shall come up the fir tree, and
instead of the brier shall come up the myrtle tree: and it shall be to the LORD for a name, for an everlasting sign that shall not be cut off.
Oddly, it is saying the exact opposite of what is commonly thought. God's higher ways and higher thoughts result in good things, not bad ones! As a doctor of faith, I resolve that this is one of the most destructive concepts in a person's doctrine and teaching.