One of the titles used to refer to Jesus in the New Testament is "Son of God."
In the Old Testament, this phrase had a general meaning of "belonging to God." It was applied to the people of Israel in general and especially its rulers (see e.g. Ex 4:22; 2 Sa 7:14).
Jesus does not refer to himself as the Son of God in the Gospels, but the term is used in the writings of Paul (e.g. Ro 1:4, 8:31) and in the epistle to the Hebrews (4:14). The Gospel of John refers to Jesus simply as "the Son," which may have a similar meaning.
Paul uses the term for both Christ and Christians, but distinguishes between the two. Christians become sons of God by adoption, but Jesus is the rightful Son of God by nature. (McGrath, Christian Theology, 327)