Luke 22:20.
All Covenants were sealed with blood ...His blood would seal the New Testament ...it had not yet been shed..
So all the gospels up to the crucification were about the law, not the New Testament.
The Old Covenant people met God in the tabernacle ..the new Covenant has men indwelled by God. The saved became living tabernacles.
The Gospels reveal the divinity and humanness of Christ, they reveal Him as Messiah.
"Christ is the Mediator of the new Testament (Matt. 26:28, Mark 14:23,24; Luke 22:20 - see Heb. 8:6-9, 12:24). Our Lord said, "This is my blood of the New Testament." Therefore, the New Testament was to be established by the shedding of His Own BLOOD. When was His blood shed? Near the END of each of the accounts in the so-called "Four Gospels" (Matthew, Mark, Luke and John), on the cross, in the year A.D.29. According to Heb. 9:16,17, a testament is not valid unless there be the death of the testator. Therefore the New Covenant did not, indeed it could not begin until AFTER HIS DEATH and the BLOOD WAS SHED."
http://www.bereanworkman.com/miscellaneous/rdhowto.htm
This is not a reformed position, it is a theological one that I learned in a "Survey of the OT " At Houghton College taught by a Mennonite PHd in Theology