I believe the problem here is a lack of Understanding on how the word One is used in Scriptures according to the author and speaker.
First of all lets take a look at the for "one" in the Greek and it is {heis} or "hen". And hen can be used mathematically and can be used as a synonym for the word "unity".
Take for example this passage in scripture:Matthew 19:5 - And said, For this cause shall a man leave father and mother, and shall cleave to his wife: and they twain shall be one{mia} flesh{sarx}?
Is a man and His wife literally One Flesh?
mia:3391 only one
sarx:4561 the body
Is not the Body of Christ which is one body comprised of many members?
1 Corinthians 12:27 - Now ye are (the body) of Christ, and (members) in particular.
A husband and his wife are one in unity (one flesh), but remain as two separate persons. Likewise with the disciples which are one in unity but remain separate as persons. God also is one in unity, however God remains as three separate persons that comprise of the Father, Son and The Holy Spirit. I have stated this in another thread that God is indentified as One in Unity as in this particular verse: James 2:19 - Thou believest that there is one{hen}(Father, Son and Holy Spirit) God; thou doest well: the devils also believe, and tremble. James said 'one' thing, however he did say 'one' person. The word for one here is placed in the neuter which intimates the social concord, and not the personal unity. Furthermore when he says one it is in reference to the identity of the (judgment) and the agreement and of the association of love in itself. In other words the Father and the Son are "one" in their love, agreement and in affection. So in conclusion Jesus' claim I and the Father are one" is clearly Jesus' intention to the Pharisees that it is to be taken as a claim of equality with the Father.
The Pharisees failed to accept the Deity of Christ and His Union with the Father due to their own logic which is "mans", in other words the their worldly wisdom blinded them to spiritual understanding.
Once again, mans ways and Gods ways are not the same!
God Bless!