Free will.
Good answer.
Is Satan a created being?
Is Satan autonomous?
Can Satan trump God?
You simply haven't thought this through to the end. And the end is always God's purpose in creating in the first place -- for His glory and the welfare of His family.
For there is nothing covered, that shall not be revealed; neither hid, that shall not be known. Therefore whatsoever ye have spoken in darkness shall be heard in the light; and that which ye have spoken in the ear in closets shall be proclaimed upon the housetops. And I say unto you my friends, Be not afraid of them that kill the body, and after that have no more that they can do. But I will forewarn you whom ye shall fear: fear Him, which after he hath killed hath power to cast into hell; yea, I say unto you, fear Him." -- Luke 12:1-5"In the mean time, when there were gathered together an innumerable multitude of people, insomuch that they trode one upon another, he began to say unto his disciples first of all, Beware ye of the leaven of the Pharisees, which is hypocrisy.
Who is Christ speaking of here? Satan or God? Who has the power to cast you into hell, or to redeem you?
Read the verses that follow this lesson, which are also found in Matthew 10. These verses are in the midst of Christ telling His flock that God loves them so much that the hairs on their head are all numbered.