Philip found Nathanael and told him, “We have found the one Moses wrote about in the Law, and about whom the prophets also wrote—Jesus of Nazareth, the son of Joseph.”
Philip wastes no time in sharing that which he has discovered. Why? Note that even with Philip’s limited capabilities he is able to win one to Christ. Note also the use of the word “we” by Philip; he has already grouped himself with the other disciples.
Nathanael’s name is not found in the other gospels, while that of Bartholomew, which means “son of Tolmai,” is not found in John. They are undoubtedly the same person. Nathanael means “gift of God” and is of Hebrew origin while Bartholomew is of Aramaic origin. It was quite common to have 2 names; an example is Peter whose name was Simon Barjona, or Simon son of Jonah, before Jesus changed it.
How could this gospel call Jesus the “son of Joseph” when in this very chapter it has already called Him the “son of God?” This has been called the irony of John. He assumes his readers know that it is just Philip speaking and Philip could not yet know the details of the virgin birth.
“Moses wrote about in the law, and about whom the prophets also wrote” = the whole of the Old Testament. Specifically, Moses wrote of a Prophet like him Whom God would raise up (Deut 18:15, 34:10).
Deut 18:15 The LORD your God will raise up for you a prophet like me from among your own brothers. You must listen to him.
Deut 34:10 Since then, no prophet has risen in Israel like Moses, whom the LORD knew face to face,
Some of the Messianic prophecies are:
Gen 3:15 12:3 49:10 Deut 18:15 Psalms 2:2 45:2 68:18 69:21 110:1 118:22 132:11 Isa 2:4 7:14 9:2,7 11:10 25:8 28:16 42:1 49:6 52:14 53:2 Isa 55:4 59:16 61:1 62:11 63:1 Jer 23:5 Eze 17:22 Dan 2:34,44 7:13 9:25 Mic 5:2 Hag 2:7 Zec 3:8 6:12 9:9 11:12 12:10 13:7 Mal 3:1