John 10:30 - I and the Father are one

 John 10:30 (KJV)  I and my Father are one.

What did Jesus mean by this? If you read the following verses from the same author, we hear Jesus speak of believers being one in the Father, and in Jesus in the same way. Are Christian believes also the same essence/nature as God?

John 17:20-22 (KJV)  Neither pray I for these alone, but for them also which shall believe on me through their word;
That they all may be one; as thou, Father, art in me, and I in thee, that they also may be one in us: that the world may believe that thou hast sent me.
And the glory which thou gavest me I have given them; that they may be one, even as we are one:

I think you would agree not.

Were Paul and Apollos one "being" or "nature"?

1 Corinthians 3:6, 8 (KJV) I have planted, Apollos watered; but God gave the increase.
Now he that planteth and he that watereth are one: and every man shall receive his own reward according to his own labour.

When he says we are all one.... the below verses tell you all you need to know. And notice the last verse here where Paul emphasises there is only one God, the Father. See also 1st Corinthians 8:6.

Ephesians 4:4-6 (KJV)  There is one body, and one Spirit, even as ye are called in one hope of your calling; One Lord, one faith, one baptism, One God and Father of all, who is above all, and through all, and in you all.