HOW COULD SATAN STAND IN PAUL'S WAY?

I Thessalonians 2:2  But even after that we had suffered before, and were shamefully entreated, as ye know, at Philippi, we were bold in our God to speak unto you the gospel of God with much contention. (KJV) I Thessalonians 2:18  Wherefore we would have come unto you, even I Paul, once and again; but Satan hindered us. (KJV)

The assumption of contradiction is that if Paul was doing God's work, how could satan hinder him?  This is more a theological question than a contradiction.  Let me just say that if satan is putting obstacles in your path, then you're on the right path.  The Bible acknowledges that satan has much power in this world, and it was evidently worldly obstacles that hindered him.  Not a contradiction.