When Stephen saw Jesus sitting on the right hand of God, is it they are separate in person? Jesus sitting as one person and God himself as one person? Are they separate in body or not?
Let’s read Acts 7:54-56, 59, “When they (the Jews) heard these things they were cut to the heart, and they gnashed on him (Stephen) with their teeth. But he, being full of the HOLY SPIRIT, gazed into heaven and saw the glory of God, and JESUS standing at the right hand of GOD, and said, ‘Look! I see the heavens opened and the Son of Man standing at the right hand of GOD!’…and they stoned Stephen as he was calling on GOD and saying, ‘LORD JESUS, receive my spirit’” (NKJV).
In this passage we have the truth of the TRINITY, which literally means “Three in One.” When we speak of the Holy Trinity, we mean that “God is ONE God who at the same time subsists in THREE Persons: The Father, the Son, and the Holy Spirit. We saw that Stephen was “full of the HOLY SPIRIT.” That is one Person in the Godhead. Then we read that he saw “Jesus standing at the right hand of God.” Jesus is another Person in the Godhead, for as Stephen was dying, he called Jesus “LORD.” And lastly, we read of God, who in this verse and many others in the New Testament, is “God the FATHER.” We have other passages of Scripture which teach that God is a Triune God. Perhaps the most well-known verse is Matthew 28:19 where Jesus said to His disciples, “Go therefore and make disciples of all the nations, baptizing them in the NAME of the FATHER and of the SON and of the HOLY SPIRIT.” Notice, the word “name” is singular, for it refers to “one God,” but that it goes on to speak of “the FATHER, the SON and the HOLY SPIRIT,” the three Persons of the Godhead. So, to answer your good question, Jesus and God the Father are indeed “separate in person”; they are “two of the three Persons” who make up the Triune God.
You also asked, “Are they separate in body or not?” We have already seen that Jesus is a separate Person from God the Father. Now let’s consider why He is called Jesus. In John 1:1 & 14 we read, “In the beginning was the Word, and the Word was with God, and the Word was God…And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace and truth.” Here we learn the amazing truth of the “Incarnation of the Word, the only begotten Son of God.” Before Jesus became a Man He had always existed as the eternal Word, the only begotten Son of God with God the Father in heaven. Yet God the Father sent His Son to earth to be the Savior of the world, as we read in 1st John 4:14, “And we have seen and testify that the Father sent the Son as Savior of the world.” God the Father wanted to save mankind from their sin so He devised a plan whereby His Son would become a Man to take man’s place in judgment on the cross of Calvary. The Son of God submitted to the Father’s plan and willingly came to earth and “became flesh and dwelt among us.” Before He was born, Joseph was told by an angel, “And she (Mary) will bring forth a Son, and you shall call His name JESUS, for He will save His people from their sins” (Matthew 1:21). At His birth we read, “And he (Joseph) called His name JESUS (verse 25). His very name means SAVIOR! And on the cross, He did the work to save sinners by “dying for our sins” (1st Corinthians 15:3). The moment a sinner “believes on His name” he/she is saved and becomes a child of God. “But as many as received Him, to them He gave the right to become the children of God, to THOSE WHO BELIEVE IN HIS NAME” (John 1:12).
What we are seeing in these passages is the fact that the Son of God was the only Person of the Triune God who became a Man, with a real body of flesh and blood. God the Father and God the Holy Spirit never “became flesh”; they have remained “a spirit,” which is WHAT GOD IS. “God is a spirit; and they who worship him must worship him in spirit and truth” (John 4:24…DARBY Version). Yet the Son of God, in love for you and me, became a true Man with a real body, and even though He is also God (see John 20:26-29 with 1st John 5:20), He will remain a Man for all eternity. “Jesus Christ is the same yesterday, today and forever” (Hebrews 13:8). Have you believed on His name? If so, you are a child of God, and you will one day see Jesus “face-to-face,” and like Thomas of old you will declare, “My Lord and my God” (John 20:28). Stephen was privileged to see Him “standing at the right hand of God” while he was being martyred for his faith, but the day is coming when all believers will also see Him “standing at the right hand of God,” for Revelation 5:6 declares, “And I looked, and behold, in the midst of the throne…and in the midst of the elders, STOOD A LAMB AS THOUGH IT HAD BEEN SLAIN.” What a sight that will be! He will bear the scars received at Calvary so we will forever be reminded of the fact that the Son of God “became flesh” so He could lay down His life on the cross to “save us from our sins.” (487.1) (DO)