Miracles may or may not happen today. God works as He wills.
If God still is in the miracle business, what do you suppose happens to those who, for whatever reason or motivation, call the work of God the work of Satan?
This is irrelevant. We are all sinners and imperfect. If we are clothed in Jesus' righteousness, we are forgiven. If not, we are condemned.
Why would Satan do miracles that people then believe are proof of God and strengthen their faith and belief in God?
Ah, that's the rub. Satan would do miracles to draw us away from God. He wouldn't have to make a major change, just a slight addition is enough. Even the snake in the garden quoted God, but with a slight addition. God said "eat and you will die". Satan quoted as "eat or touch and you will die". Something can seem like it is from God, but the slight change or small addition makes a world of difference.
Seems like that would work against him and his own interests. Why would Satan do that?
Satan doesn't work to increase faith in God. He works to twist and pervert. He adds small little bits and slowly whittles away at the core, until only the little bits are left and the core is lost.
I've not found this in the Bible. What I found is Genesis 3:1-7:
The Fall of ManThe rest of your post is interesting, but the logic you've laid out is confusing to me and my limited understanding.1 Now the serpent was more crafty than any of the wild animals the LORD God had made.
He said to the woman, "Did God really say, 'You must not eat from any tree in the garden'?"
2 The woman said to the serpent, "We may eat fruit from the trees in the garden, 3 but God did say, 'You must not eat fruit from the tree that is in the middle of the garden, and you must not touch it, or you will die.'"
4 "You will not surely die," the serpent said to the woman.
5 "For God knows that when you eat of it your eyes will be opened, and you will be like God, knowing good and evil."
Thanks for trying to help me out by answering the questions in my post.
Uh...
You'd best re-read chapter 3 of Genesis...