I truly believe that Jesus is the Only Begotten Son of God but I believe that the Sriptures teach that he did not exist as a person until his birth of Mary.
Who and what do you believe that "The Only-Begotten Son" is?
The Scriptures (all the way through the New Testament) teach that The Son of God (The Word/Logos) existed before He came to earth, and I am going to post several Scriptures right here which shows this clearly:
John 1:1-3: I n the beginning was the Word, and the Word was with God, and the Word was God. He was in the beginning with God. All things were made through Him, and without Him nothing was made that was made.
John 1:10: He was in the world, and the world was made through Him, and the world did not know Him.
John 1:14-18: 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. John bore witness of Him and cried out, saying, "This was He of whom I said, 'He who comes after me is preferred before me, for He was before me.'" And of His fullness we have all received, and grace for grace. For the law was given through Moses, but grace and truth came through Jesus Christ. No one has seen God at any time. The only begotten Son, who is in the bosom of the Father, He has declared Him.
John 3:13: No one has ascended to heaven but He who came down from heaven, that is, the Son of Man who is in heaven.
John 6:38-42: For I have come down from heaven, not to do My own will, but the will of Him who sent Me. This is the will of the Father who sent Me, that of all He has given Me I should lose nothing, but should raise it up at the last day. And this is the will of Him who sent Me, that everyone who sees the Son and believes in Him may have everlasting life; and I will raise him up at the last day." The Jews then complained about Him, because He said, "I am the bread which came down from heaven." And they said, "Is not this Jesus, the son of Joseph, whose father and mother we know? How is it then that He says, 'I have come down from heaven'?"
John 6:46-51: Not that anyone has seen the Father, except He who is from God; He has seen the Father. Most assuredly, I say to you, he who believes in Me has everlasting life. I am the bread of life. Your fathers ate the manna in the wilderness, and are dead. This is the bread which comes down from heaven, that one may eat of it and not die. I am the living bread which came down from heaven. If anyone eats of this bread, he will live forever; and the bread that I shall give is My flesh, which I shall give for the life of the world."
John 8:14: Jesus answered and said to them, "Even if I bear witness of Myself, My witness is true, for I know where I came from and where I am going; but you do not know where I come from and where I am going.
John 8:23-24: And He said to them, "You are from beneath; I am from above. You are of this world; I am not of this world. Therefore I said to you that you will die in your sins; for if you do not believe that I AM, you will die in your sins."
John 8:56-59: Your father Abraham rejoiced to see My day, and he saw it and was glad." Then the Jews said to Him, "You are not yet fifty years old, and have You seen Abraham?" Jesus said to them, "Most assuredly, I say to you, before Abraham was, I AM." Then they took up stones to throw at Him; but Jesus hid Himself and went out of the temple, going through the midst of them, and so passed by.
John 13:3: Jesus, knowing that the Father had given all things into His hands, and that He had come from God and was going to God
John 16:27-28: for the Father Himself loves you, because you have loved Me, and have believed that I came forth from God. I came forth from the Father and have come into the world. Again, I leave the world and go to the Father."
John 17:5: And now, O Father, glorify Me together with Yourself, with the glory which I had with You before the world was.
John 17:24: "Father, I desire that they also whom You gave Me may be with Me where I am, that they may behold My glory which You have given Me; for You loved Me before the foundation of the world.
Philippians 2:5-11: Let this mind be in you which was also in Christ Jesus, who, being in the form of God, did not consider it robbery to be equal with God, but made Himself of no reputation, taking the form of a bondservant, and coming in the likeness of men. And being found in appearance as a man, He humbled Himself and became obedient to the point of death, even the death of the cross. Therefore God also has highly exalted Him and given Him the name which is above every name, that at the name of Jesus every knee should bow, of those in heaven, and of those on earth, and of those under the earth, and that every tongue should confess that Jesus Christ is Lord, to the glory of God the Father.
1st Timothy 3:16: And without controversy great is the mystery of godliness: God was manifested in the flesh, Justified in the Spirit, Seen by angels, Preached among the Gentiles, Believed on in the world, Received up in glory.
Titus 2:13: Looking for that blessed hope, and the glorious appearing of the great God and our Savior Jesus Christ
Hebrews 1:1-3: God, who at various times and in various ways spoke in time past to the fathers by the prophets, has in these last days spoken to us by His Son, whom He has appointed heir of all things, through whom also He made the worlds; who being the brightness of His glory and the express image of His person, and upholding all things by the word of His power, when He had by Himself purged our sins, sat down at the right hand of the Majesty on high
Hebrews 1:8-10: But to the Son He says: "Your throne, O God, is forever and ever; a scepter of righteousness is the scepter of Your kingdom. You have loved righteousness and hated lawlessness; therefore God, Your God, has anointed You with the oil of gladness more than Your companions." And: "You, Lord, in the beginning laid the foundation of the earth, and the heavens are the work of Your hands.
The Old Testament also teaches that The Messiah is the Eternal God:
Micah 5:2: "But you, Bethlehem Ephrathah, though you are little among the thousands of Judah, yet out of you shall come forth to Me The One to be Ruler in Israel, whose goings forth are from of old, from everlasting."
Isaiah 9:6: For unto us a Child is born, unto us a Son is given; and the government will be upon His shoulder. And His name will be called Wonderful, Counselor, Mighty God, Everlasting Father, Prince of Peace.