You should read the Bible instead of trying to show that some things Christians believe are incorrect. We can do the same with Muslims.
What does the Bible tell us about God?
Deuteronomy 6:4-5
4 "Hear, O Israel! The LORD is our God, the LORD is one! 5 "And you shall love the LORD your God with all your heart and with all your soul and with all your might. NAS
Mark 12:29-30
29 Jesus answered, "The foremost is, 'Hear, O Israel! The Lord our God is one Lord; 30 and you shall love the Lord your God with all your heart, and with all your soul, and with all your mind, and with all your strength.'
NAS
James 2:19
19 You believe that God is one. You do well; the demons also believe, and shudder. NAS
John 5:44
44 "How can you believe, when you receive glory from one another, and you do not seek the glory that is from the one and only God?
NAS
John 17:3
3 "And this is eternal life, that they may know Thee, the only true God, and Jesus Christ whom Thou hast sent.
NAS
Galatians 3:20
20 Now a mediator is not for one party only; whereas God is only one.
NAS