Oneness is in The New Man which is in Christ

Ephesians 4:3-6  Endeavouring to keep the unity of the Spirit in the bond of peace.

4 There is one body, and one Spirit, even as ye are called in one hope of your calling;

5 One Lord, one faith, one baptism,

6 One God and Father of all, who is above all, and through all, and in you all.

Ephesians 4:24 And that ye put on the new man, which after God is created in righteousness and true holiness.

Colossians 3:10  And have put on the new man, which is renewed in knowledge after the image of him that created him:

Ephesians 2:1-7  And you hath he quickened, who were dead in trespasses and sins;

2 Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience:

3 Among whom also we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others.

4 But God, who is rich in mercy, for his great love wherewith he loved us,

5 Even when we were dead in sins, hath quickened us together with Christ, (by grace ye are saved;)

6 And hath raised us up together, and made us sit together in heavenly places in Christ Jesus:

7 That in the ages to come he might shew the exceeding riches of his grace in his kindness toward us through Christ Jesus.

2 Corinthians 5:17 Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new.