What does it mean when God says 'I will' in Scripture?
When God says 'I will' in Scripture, it is a promise, a divine commitment, not a human resolution. It establishes covenant certainty. In context, God promised Abraham and Sarah a son, Isaac, and said He would establish His covenant with him as an everlasting covenant.
Les explains that whenever there is an 'I will' from God in Scripture, it is a promise, not a mere wish. In Genesis 17, God says, 'I will bless her,' 'I will give thee a son also of her,' and 'I will establish my covenant with him for an everlasting covenant.' Abraham laughed because he was a hundred and Sarah ninety, but God's word remained sure. Abraham reverted to the energy of the flesh, asking that Ishmael might live before Him, but God refuted him and specified Sarah's son Isaac as the promised son. Thus God's 'I will' carries covenant certainty and identifies Isaac as the promised son.
And God said, Sarah thy wife shall bear thee a son indeed; and thou shalt call his name Isaac: and I will establish my covenant with him for an everlasting covenant, and with his seed after him.