He is allowed to do certain damage for a very limited time now in the end times. Then He will be locked up for 1000 years.
When the Lord wants to imprison Satan, nothing in the universe can stop Him. He is LETTING evil rise so that the Saints can be tried and refined to get ready for Heaven. After that job is done, there is no reason to have Satan walking around. The devil is doing THE LORDs work right now. You just don't see the big picture. Oh, and the evil will get FAR worse than now. You haven't seen anything yet.