Perhaps the best argument (I’ve heard) for the deity of Jesus is that of the necessity of the Trinity.

Therefore as God with perfect clearness, fullness and strength, understands Himself, views His own essence (in which there is no distinction of substance and act but which is wholly substance and wholly act), that idea which God hath of Himself is absolutely Himself. This representation of the Divine nature and essence is the Divine nature and essence again: so that by God’s thinking of the Deity must certainly be generated. Hereby there is another person begotten, there is another Infinite Eternal Almighty and most holy and the same God, the very same Divine nature. 

And this Person is the second person in the Trinity, the Only Begotten and dearly Beloved Son of God; He is the eternal, necessary, perfect, substantial and personal idea which God hath of Himself; and that it is so seems to me to be abundantly confirmed by the Word of God.

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The Godhead being thus begotten by God’s loving an idea of Himself and shewing forth in a distinct subsistence or person in that idea, there proceeds a most pure act, and an infinitely holy and sacred energy arises between the Father and Son in mutually loving and delighting in each other, for their love and joy is mutual, (Prov. 8:30) “I was daily His delight rejoicing always before Him.” This is the eternal and most perfect and essential act of the Divine nature, wherein the Godhead acts to an infinite degree and in the most perfect manner possible. The Deity becomes all act, the Divine essence itself flows out and is as it were breathed forth in love and joy. So that the Godhead therein stands forth in yet another manner of subsistence, and there proceeds the third Person in the Trinity, the Holy Spirit, viz., the Deity in act, for there is no other act but the act of the will.

He must be triune! Therefore, we must have another embodiment of God’s essence (His virtue, nature, attributes, etc.), which, by the aid of many sources (historical, archaeological, etc.), we can reason to be Jesus.

 

Check out these works on the Trinity:

Jonathan Edward’s Unpublished Essay on the Trinity (which I quoted above) FREE!!!
C.S. Lewis’s Beyond Personality
Daniel Fuller’s The Unity of the Bible (Which, in one chapter, often quotes both authors)