I do not understand the meaning of Christ being the Son of God, as Christians believe. What do they mean by that? Does this mean that God has married and fathered children?
God forbid!! How can any creature believe that Almighty God has married and fathered children?
This issue puzzles all among our dear Muslims who do not yet know the real truth, and we thank you for asking us this vital question. Objectivity and discernment are of great importance in understanding the answer to that questions. When Christians say that Christ is the Son of God , the significance of sonship here is different from our human conception because the sonship of Christ to God is not sonship in the human or physician meaning. God forbid that the Almighty, Jesus with His infinite power and infinite knowledge, the Creator of the Universe and all that is in it, human, animal, vegetable and mineral, should be on a level with mankind. Man is a creature of the earth, but God is an everlasting being (Deuteronomy 32:40). Moreover, the Holy Bible describes God as Omnipotent, and as a Spirit without a body, saying, "For God is Spirit, so those who worship him must worship in spirit and in truth" (John 4:24). From this we deduce that God is not a material being but a spiritual being. Therefore God has not married and has not fathered children, and this is the essence of Christian doctrine. Everyone who believes that Christ's sonship to God is a physical sonship is mistaken, because God is one, He has not fathered children and He was not born. God did not father children and He was not born, but Christ is the Son of God.
Christians in no way believe that Christ is the Son of God from the physical point of view, or in a literal human sense, i.e., that God married and fathered children. But Christ is the Son of God solely from the spiritual point of view. Christ came into the world to fulfill God's will, to proclaim the message of love and peace, and to redeem humanity from the curse of sin. And we know that Christ was conceived by the Holy Spirit that is by the Spirit of God (Matthew 1:20), and was born of a pure virgin who did not know a man, so He is the "Holy One sent from God" (Mark 1:24). And this means that Christ is nobler than a mere man, or an ordinary prophet. He was conceived in a miraculous way, and was born in a miraculous way in which nobody else was born, as was stated in the gospel of John. "Humans can reproduce only human life, but the Holy Spirit gives new life from heaven" (John 3:6). So Christ is the Holy One sent from God. He is the Word of God who became human, and a Spirit from Him.
The reason for calling Christ the "Son of God"
Christians did not call Christ the "Son of God," but the Almighty God Himself called Him by this unique name. And we can prove this, of course, from God's words. And since we believe in God the Omnipotent, and accept His promises as true, we have confidence in all His words found on the pages of the Holy Bible. In the Holy Bible we read that when Christ was baptized in the River Jordan the heavens were opened to Him, and the Spirit of God descended like a dove and settled on Him, and a voice came from heaven saying, "This is my beloved Son, and I am fully pleased with him." (Matthew 3:17). And this voice is the voice of God, who has infinite power, and by that voice God confirmed that Christ is His Son, by the Spirit, so He is the Word of God, and a Spirit from Him.
Christ was called the "Son of God" before He was born
The Holy Bible is full of assurances that Christ is the Son of God, and that Christ is the Son of God, and He was called by that name before He was born. When the angel Gabriel came to the Virgin Mary, to give her the good news that she would conceive and give birth to a son, Mary was afraid, so the angel told her, "Don't be frightened, Mary, for God has decided to bless you! You will become pregnant and have a son, and you are to name him Jesus. He will be very great and will be called the Son of the Most High…" (Luke 1:30-32). "Mary asked the angel, "But how can I have a baby? I am a virgin." The angel replied, "The Holy Spirit will come upon you, and the power of the Most High will overshadow you. So the baby born to you will be holy, and he will be called the Son of God" (Luke 1:34-35). And when Christ returned from the land of Egypt with Joseph and Mary, His mother, after the death of King Herod who had determined to kill Jesus in order to be free of Him, the return of Christ was a fulfillment of the prophecy of the prophet Hosea, which said, "I called my son out of Egypt" (Hosea 11:1 and Matthew 2:15). It is known that this prophecy was delivered by Hosea, one of the Old Testament prophets, hundreds of years before Jesus was born. It should be taken into consideration that the Christians faith is based on the fact that Christ, the Son of God, is the Savior of the world from sin, and that preaching about Christ centers on the person of Christ the Savior, the Son of God, about whom the gospel of John says, "So the Word became human and lived here on earth amount us. He was full of unfailing love and faithfulness" (John 1:14).
So we hope that the answer is clear, that the sonship of Christ to God is a spiritual sonship, and not physical or material.