In John 1:14,18, 3:16,18, and Hebrews 5:5 we see Jesus Christ being referred to as the only begotten Son of God.
In Acts 13:33 and Psalms 2:7 we see how David Prophesied of Christ being the only begotten Son of God.
As believers in Christ we are referred to as adopted sons of God, when we are led by the Spirit of God. We are heirs of God through and with Christ Jesus.
"Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will,” -Ephesians 1:5
“For as many as are led by the Spirit of God, they are the sons of God. For ye have not received the spirit of bondage again to fear; but ye have received the Spirit of adoption, whereby we cry, Abba, Father. … And if children, then heirs; heirs of God, and joint-heirs with Christ; if so be that we suffer with him, that we may be also glorified together.” - Romans 8:14-15,17
“And because ye are sons, God hath sent forth the Spirit of his Son into your hearts, crying, Abba, Father. Wherefore thou art no more a servant, but a son; and if a son, then an heir of God through Christ. - Galatians 4:6-7