How do we know Jesus is God? We know this, not only because the Bible calls him 
God (Is 9:6; Jer 23:6; John 1:1; 8:58; 20:28; Tit 2:13; 2 Pet 1:1). We also know this because the Bible describes Jesus in a way that can only describe God. I would like to focus specifically on Micah 5:2.
Moses describes God’s origin as from everlasting to everlasting in Psalm 90:2. He is eternal, with no beginning and no end. The Hebrew he uses for “from everlasting to everlasting” is me owlam ad owlam. Micah 5:2 says that the coming ruler of Israel would come from Bethlehem, and his going forth is from of old, from the days of everlasting, using the same word mi-ymey (from days) owlam (everlasting), the exact way Moses describes God’s origin.
But why does he say “days” in Micah? This is a common way of speaking of eternity. David describes this eternal day in Psalm 2:7 when he speaks of God’s decree to the Son: “You are my Son. Today (ha-yom) I have begotten you.” This is why Micah says that his going forth (mo-tsa-ow) is from the days of everlasting. Micah also says that he is from of old, using the Hebrew word qedem. This word is often translated as “eastward” or “from the east”(Gen 2:8; 3:24; 10:30; 11:2; 12:8; 13:14; 25:6; Exod 27:13; 38:13; Lev 1:16). Or it can describe a general direction (Job 23:8). Isaiah uses the term when rebuking false faith in Pharaoh, “How can you say to Pharaoh, ‘I am a son of the wise, a son of ancient (qedem) kings’?” He likewise uses it to rebuke other false trusts in supposed eternal kingdoms (Is 23:7).
But again, this term, while used in various ways, is used to describe God, and specifically his kingly rule (Ps 74:12). After describing how God rescues him from those who attack him, David continues in Psalm 55:19: “God shall afflict them, he who dwells from of old (qedem).” Qedem also describes God’s eternal act of redemption (Ps 74:2), and both owlam and qedem describe God’s relation to Wisdom (Prov 8:22-23), a passage which St. John seems to echo when he says “In the beginning was the Word, and the Word was with God, and the Word was God. (John 1:1)” How can he conclude that the Word (or Wisdom; cf. 1 Cor 1:30) is God? Because he is described with the same attributes as God in the Old Testament.
God himself is described in the Psalms as being from everlasting and dwelling as well as ruling from of old. This precisely describes the coming ruler of Bethlehem in Micah 5:2.
The Jews stumble over this because they know the shama from Deuteronomy 6:4: “Shama Israel! YHWH Elohenu, YHWH ehad,” that is, “Hear Israel! The LORD our God, the LORD is one.” They stumble over these distinct divine figures since God is one. And yet, this is how the Scriptures speak. He is king from of old. He is God from everlasting to everlasting. And yet, from Bethlehem there comes one who fits this exact description. And, in fact, we cannot know God apart from this Wisdom God, which goes forth from of old. We cannot know the Lord apart from the Son. So as the Psalmist says (Ps 2:12), “Kiss the Son, lest he be angry, for his wrath is kindled but a little. Blessed is everyone who trusts in him.”