How come some believe God has a Son and they don't believe that Jesus Christ is God? almighty

A lot of people want to understand the word of God without the Holy Spirit. This is not possible, NO ONE will be able to understand God's word unless you have been born again and have the Holy Spirit inside you. Put yourself like a baby, and submit to God. Only faith pleases God. When you stop leaning on your own understanding and come to the realization that Jesus Christ is the Alpha and Omega, and there is no there God besides him, you will see a change in you and your life you could never have imagined.
As long as you try to make it make sense in your head, and keep believing that Jesus Christ could not be who he says HE is, you will die in your sin. Let me use this Example: you are caught speeding and a policeman pulls you over and gives you a ticket and says you need to appear in court. You go before the judge and he says that you have broken the law and now a fine must be paid. Then a man from the back of the room stands up and says "I will pay the fine for you". The judge lets the man pay the fine for you because he doesn't care who pays it as long as it is paid. So you see, if you have ever broken one of God's laws, the penalty is death. When you go before God, since he is a righteous and just God, the penalty has to be paid. This is why Jesus came and died for your sins. God knew a penalty had to be paid and decided to pay it himself. So, When it is time for your judgment and go in front of God, if you have a relationship and have accepted the sacrifice Jesus made, then your penalty has been paid and you are free.

Jesus Christ said; He is the Way, the Truth, and He is the Life. He is in the father and the father is in Him. He is one with the Father. He is the Resurrection. He is the only one who can forgive your sin because He is the one that died for your sins. He is the one that took your place for, every time that you sinned against God. Jesus Christ said You will die in your sin unless you know that I AM HE.
Whoever believes in Him is well able to say, greater is HE than he that is in the world. Stop doubting, believe.
Jesus said the devil stands condemned. He has no choice. The devil would give anything if he had a chance, but you have a many many many chances.
Stop trying to make it to make make sense in your little heard. You will never understand unless God believe by faith and humble yourself.