Heidelberg Catechism - Lord's Day 13

33. Q . Why is he called God’s “only begotten Son” when we also are God’s children?
      A. Because Christ alone is the eternal, natural Son of God. We, however, are adopted children of God— adopted by grace through Christ.

34. Q . Why do you call him “our Lord”?
      A. Because— not with gold or silver, but with his precious blood—he has set us free from sin and from the tyranny of the devil, and has bought us, body and soul, to be his very own.