Okay, one problem with Christianity is that people always assume magic is bad. I concede, sorcery and stuff dealing with consorting with demons is bad, but magic defined as "miraculous events" is part of God's legacy.
As for people who weren't Christian having powers, keep in mind that we are children of God. In Greek mythology, that's called a demigod. And Jesus even said in John 14:12 "Very truly I tell you, whoever believes in me will do the works I have been doing, and they will do even greater things than these, because I am going to the Father."
Magic isn't satanic, nor is it godly. It's supernatural. And people on both sides use it. Remember, Satan can create nothing, he can only use what God created and twist it for evil.
As for why it isn't possible today, well the answer is simple; we cannot see what we do not believe in. And while we say we believe in God, we deny that miracles still happen. If most people saw a person use telekinesis, they would say either that it's a trick or that it's the Devil. Few people give God credit for magic anymore. We can't see miracles because we don't believe in them. I mean, if people can believe the world is flat and find "evidence" to support it, then we certainly can find ways to explain away miracles.