It is the Spirit who gives life; the flesh profits nothing; the words that I have spoken to you are spirit and are life. – John 6:63
Jesus spoke the words above within the context of challenging His followers to eat His flesh and drink His blood. Of course, He wasn’t advocating cannibalism and the crowd probably understood that much, but they still struggled to grasp this difficult teaching. They could not discern His words because their “flesh” (their individual belief systems that had been developed apart from a relationship with God) hindered their understanding.
Almost every decision we make in life is affected by thoughts of self-preservation. Think about it. What we eat, where we go, with whom we spend time, dare I say, even where we choose to worship, almost every decision is selfishly motivated.
Jesus calls His disciples to give everything up for a life in the Spirit, a life devoid of concerns of the flesh. In order to follow Christ, we must take up our cross daily. We must crucify our worldly belief system every single moment. Apparently, this is the only life that the Lord deems worth living.
Our abandonment must be to God, not to man, and our trust must be in Him, not in any arm of flesh, or we shall fail at the first trial. – Hannah Whitall Smith