Isaac had some maturity in life, but not very much. Although he blessed, he blessed blindly (27:21-29). His blessing was according to his natural taste (27:1-4). He blessed blindly, not only physically but also spiritually, because he had been blinded by his natural taste. However, he did bless by faith (Heb. 11:20). He had said that his soul would bless, but eventually it was not his soul that blessed; it was his spirit that bestowed the blessing, and his blessing became a prophecy. No one can prophesy in the soul. If we would prophesy, we must be in our spirit. Thus, Isaac did bless in the spirit by faith.
Faith does not depend upon what we are; it depends upon what we see. Whenever you want to exercise faith, you should not look at yourself, at what you are, nor at your environment. You must look at what God is and to what He says. Then you will be able to exercise your faith in God and in His word. Isaac blessed by faith in this way. According to his situation, he was not qualified to have faith. But he did not consider what he was; he looked away to God and to God's promise, blessing his son by faith and in the spirit. If we would have faith, we must look away from ourselves, for if we look at ourselves, faith will disappear. Look unto God and see what He has spoken in His word. Then simply utter what God has already spoken. This is faith. Isaac blessed his son in this way.
Although there is no hint in the Bible that Isaac was very spiritual, he did not die in a miserable condition. He died in faith at the fullness of days (35:28-29). This is proved by the fact that his sons buried him, along with his wife Rebekah, in the cave of Machpelah (49:30-32). Before he died, he must have charged his sons to bury him in the cave of Machpelah, where Abraham and Sarah were buried. This proves that Isaac had the faith of Abraham.