Biblical Proof
Matthew 3:17 And lo a voice from heaven, saying, This is my beloved Son, in whom I am well pleased.
When Jesus was baptized, the people could hear a voice from heaven speaking. The Father is in heaven. He spoke and called Jesus his beloved Son!
1st John 1:20 And we know that the Son of God is come, and hath given us an understanding, that we may know him that is true, and we are in him that is true, even in his Son Jesus Christ. This is the true God, and eternal life.
The above passages declare God is Jesus’ father; therefore, Jesus Christ is the Son of God!