Oneness can be hard to grasp for some. Many "morph" the Father and Son together in such a way that Christ's humanity, the man Christ Jesus, loses distinction. Maybe this description of Oneness will help you to at least grasp the concept better.
Put yourself into the shoes of a disciple who walked with Christ...
Imagine actually walking with Jesus for three years. How would you experience Christ's Oneness with the Father first hand? I like to explain it like this:
If you walked the earth with Jesus, you'd get to know Him as a man. He'd teach. He'd laugh. He'd eat. He'd use the restroom. He'd sleep. He'd rest. He'd pray to, and speak of, His Heavenly Father. He'd fast. He'd cry. He'd sweat. He'd bleed. However... at times you'd feel something otherworldly emanating from deep within Him. Something emanating from the very core of His being. Something powerful. Something that has authority over all creation. Something that speaks to the winds... bringing them into total and absolute obedience. Something that raises the dead and heals all manner of sickness. Something indescribable. Something "other". This would be the Father Himself at the core of Christ's own person. You'd realize that this man is far more than just a mere man. You'd realize that this man is...
also God.
However, keep in mind...God did not reside in Christ as though He were merely a human vehicle. He didn't reside in Christ as a cat in a box. That would be Unitarianism. No, God abides in and permeates Christ's very being. A Oneness so complete, so majestic, and so divine that in Christ it can be said that God became a man... and that this very same man (from conception) was also God. In Christ Jesus, God elevated human nature into union with His own divine nature. In addition, His very own divine nature condescended to establish union with human nature.
No other religion elevates Christ to such an infinite height of majesty and honor. No other religion expresses Christ's true person to such an infinite degree. Most religions merely make Christ a prophet or seek to establish Him as being some second co-eternal divine being or person. No... Christ was not just a prophet. Christ was not a second co-eternal divine being or person. Christ also wasn't God shape-shifted or morphed into the mere appearance of a man who only pretended to pray. Christ was the authentic human tabernacle of God Himself. To deny this imperils the soul... and reduces Christ to being either a lunatic or a liar.
All authority and power has been delivered to Christ Jesus. He will judge Krishna. He will judge Buddha. He will judge Mohammed. He will judge Nanak. He will judge the followers of every false prophet and madman. He will judge all men in accordance to the Father's will as it relates to the Gospel. Through Him, the Father will judge. Because they are one.
Let us see how Jesus Himself describes His Oneness with the Father:
John 10:30
30 I and my Father are one. (KJV)
John 10:38
38 But if I do, though ye believe not me, believe the works: that ye may know, and believe, that the Father is in me, and I in him. (KJV)
John 12:45
45 And he that seeth me seeth him that sent me. (KJV)
John 14:7-10
7 If ye had known me, ye should have known my Father also: and from henceforth ye know him, and have seen him.
8 Philip saith unto him, Lord, shew us the Father, and it sufficeth us.
9 Jesus saith unto him, Have I been so long time with you, and yet hast thou not known me, Philip? he that hath seen me hath seen the Father; and how sayest thou then, Shew us the Father?
10 Believest thou not that I am in the Father, and the Father in me? the words that I speak unto you I speak not of myself: but the Father that dwelleth in me, he doeth the works. (KJV)
I've included an image to explain the concept visually.