While at seminary, my Old Testament professor made what I thought at the time was an audacious claim — we know more about Christ from the Old Testament than the New. Given that the NT specifically deals with the life, crucifixion and resurrection of Christ, it seemed unlikely to me that there is any way that the OT could have more information on Him. Then I began to read the Fathers of the Church.
One might be surprised to find that the Fathers, especially those that lived during the great Christological controversies of the 4th and 5th centuries, spend an awful lot of their time dealing with the OT and what we know about Christ from the OT. St. Ambrose, being one of those 4th century Fathers who had to fight Arianism, is no different.
He begins his treatise on the Holy Spirit meditating upon the story of Gideon from the sixth chapter of Judges. Ambrose focuses on the sacrifices Gideon makes to God:
[Gideon], instructed and foreknowing what was to be, observes the heavenly mysteries, and therefore, according to the warning, slew the bullock destined by his father to idols, and himself offered to God another bullock seven years old. By doing which he most plainly showed that after the coming of the Lord all Gentile sacrifices should be done away, and that only the sacrifice of the Lord’s passion should be offered for the redemption of the people. For that bullock was, in a type, Christ, in Whom, as Esaias said, dwelt the fulness of the seven gifts of the Spirit. This bullock Abraham also offered when he saw the day of the Lord and was glad. He it is Who was offered at one time in the type of a kid, at another in that of a sheep, at another in that of a bullock. Of a kid, because He is a sacrifice for sin; of a sheep, because He is an unresisting victim; of a bullock, because He is a victim without blemish.
Thus, the sacrificial cult of the OT was in preparation for the coming sacrifice of Christ on the Cross. Each type of sacrifice speaks to the purpose of Christ in His suffering and how He fulfills the Law.
I find it fascinating that Ambrose not only begins his treatise on the Holy Spirit with the OT, but with Christ on the Cross. It is a reminder for all of us that Christmas is meaningless outside the context of the OT and Cross. We cannot have or experience the resurrection without either.