Justin Taylor gave a remarkable interview with Vern Poythress for the TGC website. Poythress answers questions relating to the big picture of biblical theology and how Christ fits within the context of the Old Testament.
Since Christ is fully man, God as God had a relationship to Christ the man, and this relationship between God and the man was, in the general sense, “covenantal.” God on his part made commitments to Christ in his OT promises. Christ, in his earthly life, committed himself to following the Father’s way. This covenant between God and Christ was both “conditional”—involving the necessity of Christ’s obedience—and “unconditional”—guaranteed by God. So the words “conditional” and “unconditional” must be used with care. We have to ask ourselves not only which covenantal relation we are discussing, but what aspect of that relation.