Dear
Arizona, thank you so much for your good questions. You asked about the origin of evil. How was it possible for a creature created by God to find sin in itself? I gave a lot of thought to this matter, and I believe that I have some light from the Lord regarding this. I will share it with you, and let's see if it satisfies you.
I have come to conclusion that sin was possible because God's creation was not perfect. Only God is absolutely perfect. Everything that is not God does not have absolute perfectness. There are some verses that show us this:
He charges His angels with error (Job 4:18),
and the heavens are not pure in His sight (Job. 15:15). God's creation was good, but not perfect, and in this imperfection the possibility of sin was hidden. This is how Satan fell. And this is imperfectness Satan appealed to in man, when tempting him.
God is not a creator of evil as His creation is good. But because the creation is not perfect, sin is possible, but this possibility lies in the freedom of will. Therefore, the responsibility is on the moral agent who used his free will to activate this possibility.
Why God's new creation is His masterpiece? Because the new creation partakes of God's life and nature - and in this way partakes of His absolute perfectness -
be perfect as your heavenly Father is perfect! None of the old creation, even faithful angels, is as perfect as God. Only the church, the Body of Christ, has access to God's full perfection. This is why there will be no danger of sin anymore for us in eternity.
I hope it helps. God bless you!