As simple as it gets
Thomas [the doubter] answered him, “My Lord and my God!” Jesus said to him, “Have you believed because you have seen me? Blessed are those who have not seen and yet have believed.” John 20:28-29
Jesus doesn’t correct Thomas when Thomas calls Him God. Jesus commends him for finally believing, then blesses those who believe without requiring seeing. If Jesus wasn’t God, then this would be blasphemy. [see also Rev 5:14, Hebrews 1:6 where Jesus receives worship, which is unacceptable if He’s not God]
For the grace of God has appeared, bringing salvation for all people, training us to renounce ungodliness and worldly passions, and to live self-controlled, upright, and godly lives in the present age, waiting for our blessed hope, the appearing of the glory of our great God and Savior Jesus Christ, who gave himself for us to redeem us from all lawlessness and to purify for himself a people for his own possession who are zealous for good works. Titus 2:11-14
Jesus is God
The simple and complex answers are the same. God has come to bring salvation; training us to renounce our wicked ways and put all our hope in Jesus, our great God and Savior, who is coming back to receive His own people who are zealous for good works and eagerly waiting on Him.