The most common reason for not understanding how Jesus is God is a failure to grasp the eternal relationship between the Father, the Son and the Holy Spirit. There is only One Being of God.
Within the One Being who is God subsist the three separate persons of the Father, the Son and the Holy Spirit. At Jesus' baptism, all three persons of God were present - Jesus as the Son of God in human form, the voice of the Father heard from heaven and the Holy Spirit who descended in the form of a dove. When Jesus, the Son, died, the Father and the Holy Spirit did not also die, because all three are separate persons.
Before Jesus came to earth in human form, he already existed in heaven alongside the Father and the Holy Spirit. He was known as the Word, and as the Son of God. Read John 1:34
The Word, the Son of God, humbled himself and gave up the glory he shared in heaven alongside the Father and the Holy Spirit, to come to earth and atone for the sin of the world. Read Philippians 2:8
Jesus, who is also the Word, was there, in the beginning, at creation. It says so in John 1:1
Jesus, the Word, became flesh and dwelt with man. It says so in John 1:14
No-one has ever seen God but Jesus, who has made God known to us because he is God the One and Only. It says so in John 1:18
When Jesus walked the earth as a man, he was obedient to his Heavenly Father because he had been sent to do the will of the Father. After he died and was resurrected, he returned to be with the Father and with the Holy Spirit and is worthy of all worship.
When we worship God, we are worshipping the Father, the Son and the Holy Spirit. One Being of God, but three separate persons. Check out the illustration at the end of the link (below) which explains the eternal relationship between all three. You simply cannot have one without the other two!
But because the Jesus of the Qur'an bears no resemblance to the Jesus of the Bible, and because Islam mistakenly teaches that Jesus was a Muslim and is going to come back as a prophet of Muhammad, then no Muslim is ever going to believe the Jesus of the Bible, the Son of God who came to earth to save us from our sin. If you don't know the significance of our sin and how God views sin, then your God is not my God.
P.S. Ah, I see we are all wasting our time. You don't want to know, do you? Wonder which atheist answer you will pick?