2 Tim 1:10 explains that Jesus "brought life and immortality to light through the gospel". So although several Old Testament passages merely hinted at certain doctrines, these teachings were fully brought to light by Christ. Many concepts merely alluded to in the Old Testament, finally revealing themselves explicitly taught in the New Testament.
The following were all alluded to in the Old Testament though the Jews didn’t comprehend it fully:
Final resurrection (Ps 16:10; 17:13-15; Dan 12:1-12 = Jn 5:28)
Final judgement (Ps 96:13; Dan 7:10 = Rev 20:12)
The Messiah would be all of the following: both king and priest (Zech 6:13) and prophet (Deut 18:18) The Jews were looking for several different individuals and hadn't understood that Jesus would fulfill all three roles. (Acts 3:22; Jn 18:37; Heb 3:1)
The Messiah would be crucified (Isa 53 = Jn 19:6)
The Messiah must be killed (Dan 9:26 = Lk 9:22)
The Messiah was to be raised from the dead (Ps 16:10 + Lk 24:46)
Immortality and eternal life (Dan 12:3 = 2 Tim 1:10)
That the first covenant (10 Commandments) would be abolished and replaced by a new covenant (Jer 31:31f = Heb 8:6-13).
The Trinity (Gen 1:26 = Jn 1:1; 20:28; Mt 28:19)
Some of the concepts alluded to in the Old Testament, were misunderstood by the Jews because they misinterpreted the scriptures.. just like cults and heretical sects do today.
I have a really neat post I made earlier showing scriptures in the Old Testament where God reveals his trinue nature. Good stuff
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