Romans 8v1-17
So although we struggle now with the ‘body … dead because of sin’ we know that this same ‘mortal body’ will be raised at the end. (Similarly, in 6:5 Paul makes the point that because we are now ‘united with Jesus in a death like his’, we know that in the future ‘we will certainly also be united with him in his resurrection’).
Notice that (a) we have to ‘put to death the misdeeds of the body’ (we do not just ‘let go and let God’ do it for us), but that (b) we do not do this in our own strength (‘works of the law’) but ‘by the Spirit’. It is by the grace of God working in us that we put to death that old way of living. Notice also that we ‘put to death’ in the present continuous tense, indicating ongoing activity; this mortification of the old life cannot be done in one go, but needs a daily taking up of the cross and denial of self (