Colossians 2:8 (NKJV)
When I was a child, there was a game we played, especially in the Winter, called, "The King of the Hill". We made as big of a pile of snow as we could, and then one person would get on top of the snow pile to be the king of the hill. After that, the rest of us would do everything we could to get up the hill and knock that person off the top, so that we could be the king of the hill. Fortunately, because the snow was usually fairly soft, no one got hurt and we all had a lot of fun playing this game.
The Bible contains the information we need to learn the truth about who we are in Christ, and how that because of what Jesus did for us, we have right standing with God and we are His children. But there are a lot of Christians who are trying to play a spiritual game of king of the hill, thinking that believers have to do everything they can to get up to the top of the spiritual hill, so to speak, and conquer the devil and life's problems. The only thing is that, because of Jesus, we are already on the top of the spiritual hill!
As Paul wrote to the Colossians, we need to be careful not to let anyone "cheat" us, or literally "to carry us off as a slave". The Bible shows us what our true spiritual position in Christ is, while the wrong kind of teaching can move us away from that truth. The life of a Christian is not trying to fight our way into some spiritual position, but we need to take a stand in Christ concerning what belongs to us, and not let anything move us away from that position. We need to know who we are in Christ, what belongs to us through Jesus, and take our stand there so that nothing moves us away.