What Do We Mean When We Confess Jesus to be the Son of God?

The Bible uses the expression “son(s) of God” to designate angels, Israel, kings in the Davidic line, individual Israelites, Christians, and Jesus. What does the expression mean? The Bible calls Jesus the “one and only Son.” So what is unique about his sonship? What do they mean, and what is at stake, when Christians confess that Jesus is the Son of God?