The God of the Bible is one; the Father who made the world and has a purpose for the world he has created, he is not a multiple being. In Deuteronomy 6:4, God through Moses declares himself to be one;
“Hear O Israel, the Lord our God is one Lord.”
80% of the Bible is the Old Testament and details the history of the nation of Israel. The nation of Israel worshipped one God. It is a monotheistic religion.
The New Testament is built on the Old and Jesus Christ (a Jew) said in (John 14:28)
“My Father is greater than I .”
And in (John 10:29) speaking of God the Father, Jesus says the Father
“is greater than all.”
When Jesus says things like
“I and my father are one,”
he is not claiming equality with the Father but that he is at one with him in purpose. This is so, because he later says that his disciples will also be one with him. Look at this in John 17:22
“And the glory which thou gavest me I have given them; that they may be one, even as we are one: I in them, and thou in me, that they may be made perfect in one; and that the world may know that thou hast sent me, and hast loved them, as thou hast loved me.”
Further Reading:
Isaiah 40:13-25; Isaiah 43:10-12; Isaiah 44:6-8; Isaiah 45:5; Isaiah 46:9-10; Job 38:1-41; Job 39:1-30; Job 40:1-24; Deuteronomy 6:1-4; Mark 12:29-32; 1 Corinthians 8:4-6; Ephesians 4:6; 1 Timothy 2:5; Nehemiah 9:6; Job 26:13; Psalm 124:8; Psalm 146:6; Psalm 148:5; Isaiah 40:25-27; Jeremiah 10:12-13; Jeremiah 27:5; Jeremiah 32:17-25; Jeremiah 51:15; Acts 14:15; Acts 17:24; 1 Chronicles 29:11-14; Psalm 62:11; Psalm 145:3; Isaiah 26:4; Isaiah 40:26; Job 9:4; Job 36:5; Psalm 92:5; Psalm 104:24; Psalm 147:4-5; Isaiah 28:29; Romans 16:27; 1 Timothy 1:17; 2 Chronicles 16:9; Job 28:24; Job 34:21; Psalm 33:13-14; Psalm 44:21; Psalm 94:9; Psalm 139:7-12; Proverbs 15:3; Jeremiah 23:24; Jeremiah 32:19; Amos 9:2-3; Acts 17:27-28; Psalm 123:1; 1 Kings 8:30-39; 1 Kings 8:43; 1 Kings 8:49; Matthew 6:9; 1 Timothy 6:15-16; 1 Timothy 1:17
1 Corinthians 2:13; Hebrews 1:1; 2 Peter 1:21; 1 Corinthians 14:37; Nehemiah 9:30; John 10:35