Jesus is in the OT in person as God revealed, God made visible, God manifested as a man or "the angel of the LORD."
John 1:1-18:
I Jn 1:1-3; 5:6-8 calls Him the Word, or God expressed. This is also called a theophany which the dictionary defines as "an appearance of a god to a man or a divine manifestation." It comes from Greek "theos" meaning god and "phainen" meaning to show. In Phil 2:6 it says Jesus was in the "form of God." In
Hebrews 1:3 Jesus us called the icon (picture) of God.
Here is a note from the Amplified Bible:
"The 'angel of the Lord,' or 'of God,' or 'of his presence' is readily identified as the Lord God (
Gen 16:11,13; 22:11,12; 31:11;
Ex 3:1-6, etc.). But it is obvious that the angel of the Lord is a distinct person in Himself from God the Father (Ge 24:7;
Zech 1:12, 13;
Ex 23:20, etc.) as this verse shows. Nor does the Angel of the Lord any longer appear after Christ came in human form. He must of necessity then be one of the three-in-one Godhead. The Angel of the Lord is the visible Lord God of the OT, as Jesus Chris was of the NT. Thus His deity is clearly portrayed in the OT. There is a fascinating forecast of the coming Messiah, breaking through the dimness, with amazing consistency, at intervals from Genesis to Malachi. Abraham, Moses, the slave girl Hagar, the impoverished farmer Gideon, even the humble parents of Samson, had seen and talked with Him centuries before the herald angels proclaimed His birth in Bethlehem." (note from the Amplified Bible on
Isaiah 63:9)
Here is a note from the Criswell Bible:
"No other angel is comparable to the 'Angel of the LORD.' He spoke with authority over life. That this is a theophany, an appearance of the pre-incarnate Christ is confirmed in that (1) He specifically identifies Himself with YAHWEH on various occasions, (2) He is recognized as divine by those to whom He appears, (3) the biblical writers often call Him Yahweh, (4) the unity of the OT and NT is further enhanced by the appearance of the God-man in the OT, and (5) this interpretation supports the Triunity of the Godhead through the pre-incarnate appearance of the Son" WA Criswell in the Criswell Study Bible
Here are some appearances of Jesus as the Angel of YHWH
Gen 12:1-7 God appeared to Abram
Gen 15:1-18 Word of the Lord in a vision to Abram
Ge 16:7-16 Angel appeared to Hagar
Ge 17:1-22 Lord appeared to Abram
Ge 18:1-33 Lord appeared to Abram
Ge 21:9-21 Lord called Hagar
Ge 22:11-18 Angel called to Abraham
Ge 26:1-6 Angel appeared to Isaac
Ge 28:10-16 Lord appeared to Jacob
Ge 32:1-32 Angel wrestled with Jacob (ref
Gen 48:15-16;
Hos 12:3-5))
Ex 3:1-22 Angel appeared to Moses
Ex 24:9-12 Moses, Aaron, Nadab, Abihu, 70 elders see God
Josh 5:13-15 Angel appears to Joshua
Judges 6:11-24 Lord appeared to Gideon
Judges 13: 1-23 Angel appears to parents of Samson
Isa 6:1-13 Isaiah saw the Lord (ref
Jn 12:39-41; Ac 28:17-29)
Isa 63:7-9 Angel of His presence (ref
Ex 14:19; 23:20-23;
Num 20:16)
Isaiah 9:6 in the LXX (probably used by the Apostles and writers of the New Testament) says:
For a child is born to us, and a son is given to us, whose government is upon his shoulder: and his name is called the Angel of great counsel, Mighty one, father of the age to come, Prince of Peace. His government shall be great, and of his peace there is no end: it shall be, upon the throne of David, and upon his kingdom, to establish it, and to support it with judgment and with righteousness, from henceforth and forever.