I found this quote from the blog at Reformed Reader helpful in thinking about preaching Christ in all of Scripture. Many pastors, young and old, continue to do a disservice to the OT text by bludgeoning Christ upon every jot and tittle.To those who make it their practice to do so, I think these wise words from Sidney Greidanus are instructive:
The christocentric method complements the theocentric method of interpreting the Old Testament by seeking to do justice to the fact that God’s story of bringing his kingdom on earth is centered in Christ: Christ the center of redemptive history, Christ the center of the Scriptures. In preaching any part of Scripture, one must understand its message in the light of that center, Jesus Christ.
It should be clear by now that our concern is not to preach Christ to the exclusion of the “whole counsel of God” but rather to view the whole counsel of God, with all its teachings, laws, prophecies, and visions, in the light of Jesus Christ. At the same time, it should be evident that we must not read the incarnate Christ back into the Old Testament text, which would be eisegesis, but that we should look for legitimate ways of preaching Christ from the Old Testament in the context of the New.
Preaching Christ from the Old Testament, pgs. 227-28.
A solid reminder that while we must not allegorize Christ all over the OT, as though we could make him explicitly mentioned in every verse, we must recognize that every verse providentially exists where it is as part of a canonical Bible that centers around God’s redeeming work in none other than Christ himself. Thus to preach a given verse as though it had nothing to do with Christ and his finished work is to misunderstand the OT as Christian Scripture.