The contrast between Isaac and Ishmael is the contrast between living ‘by the power of the Spirit’, and living ‘according to the flesh.’ May God help us to live 'by the power of the Spirit' and not 'according to the flesh.'
In the face of evil unbelief and persistent opposition, Jesus spoke with tremendous assurance: ‘You are from below, I am from above; you are of this world, I am not of this world... you will die in your sins unless you believe that I am He’ (John 8:23-24). ‘As He spoke thus, many believed in Him (John 8:30) - Jesus spoke with power and love. Responding to Him in faith, we are set ‘free’ (32,36; Romans 8:2; Galatians 5:1). To receive His freedom, we must recognize our need: ‘everyone who commits sin is a slave to sin’ (John 8:34). To grow in His freedom, we must ‘continue in His Word’ (John 8:31). To religion without Christ (John 8:39,41), Jesus’ answer is emphatic: ‘You are of your father the devil... you do not hear God’s words because you are not of God’ (John 8:44,47). ‘I am’ (John 8:58; Exodus 3:14). God is in control - not men (John 8:59,20).