31And He began to teach them that the Son of Man must suffer many things, and be rejected by the elders and chief priests and scribes, and be killed, and after three days rise again. 32He spoke this word openly. Then Peter took Him aside and began to rebuke Him. 33But when He had turned around and looked at His disciples, He rebuked Peter, saying, "Get behind Me, Satan! For you are not mindful of the things of God, but the things of men."
This is a great example of how Satan works very subtly through people without them even knowing it -- people who think they are just trying to help. Have you ever seen a friend struggle with something they didn't really want to do, so you try to help them by trying to come up with a good reason why maybe they shouldn't have to do what they didn't want to do? As we know, Jesus would have preferred to let this burden be removed from him too. And here his closest follower was trying to tell Jesus it shouldn't have to happen. Jesus recognized the work of Satan, the great tempter, in Peter, even though Peter most likely thought he was just trying to help his friend, Jesus.
The good news is that Jesus easily recognizes the work of Satan within us. But does that mean we can use the excuse of "the devil made me do it"? Unfortunately, we were given freedom of choice. When we do what Satan prompts us to do, we are doing it by our own choice. Jesus wants us to follow Him, not Satan.
How do we recognize the work of Satan within us? I think it is explained in very clear terms here. When we are being mindful of things of men rather than the things of God we may be being lead by Satan. Is it OK to help a friend try to remove a burden of something they really would rather not do? Yes, unless what he is trying to avoid is for the work of God.