That they may all be one, just as you, Father, are in me, and I in you, that they also may be in us, so that the world may believe that you have sent me. The glory that you have given me I have given to them, that they may be one even as we are one, I in them and you in me, that they may become perfectly one, so that the world may know that you sent me and loved them even as you loved me. John 17:21-23
But he who is joined to the Lord becomes one spirit with him. 1 Corinthians 6:17
For if we have become united with Him in the likeness of His death, certainly we shall also be in the likeness of His resurrection, knowing this, that our old self was crucified with Him, in order that our body of sin might be done away with, so that we would no longer be slaves to sin; for he who has died is freed from sin. Romans 6:5-7
For in Christ Jesus you are all sons of God, through faith. For as many of you as were baptized into Christ have put on Christ. There is neither Jew nor Greek, there is neither slave nor free, there is no male and female, for you are all one in Christ Jesus. Galatians 3:26-28
Speaking of oneness...
Jesus said that no one can come to him unless the Father draws him. John 6:44
And that no one can come unto the Father except by Christ. John 14:6
What does oneness mean to you?