"Paul's meaning is not that the flesh, with its affections and lusts, is no longer present at all with those that have become Christians, but that a walk in the flesh should not any longer exist in the case of Christians. A walk in the Spirit might be rightly expected of believers. This is only possible for those who have crucified the flesh. The word is not slain, but crucified. It is a task of the Christian to be accomplished only by continual effort (Colossians 3:5).
"In 'crucified', however, the simple slaying is not the main idea, but the condemning, giving sentence, surrendering to infamous death. This has necessarily taken place in becoming Christ's. Fellowship with Christ involves a crucifixion of the flesh for the very reason that it is fellowship with Christ's death on the cross.
"Christ indeed has only suffered what people have deserved on account of their sinful flesh. Whoever appropriates to himself Christ's death upon the cross regards the flesh to himself no longer. For him, in Christ's death, the flesh has been crucified."