We have a tug-a-war in our souls. It's between living for ourselves and living for God. In this passage its described as a tug-a-war between our fleshly desires and the desires of the Holy Spirit Who lives in us. When we live for our fleshly desires, we do all kinds of bad things. The Judaizers (legalists) would say the only way to control our flesh is to live under the Law of Moses. In their minds, if we’re freed from the law the flesh will take over. There will be nothing to keep our flesh under control. But there is another way to gain victory over the flesh. Through the Holy Spirit. The Holy Spirit is so much better than the law because the Holy Spirit doesn’t control our flesh, He transforms it.