What is the Christian's Identity?

In "Doctrinal Discussion" Randy Bland writes:

Our identity is given to us by God the Father, through the work of Jesus on the cross. We receive this work of salvation by grace through faith. The Father declares that we are righteous, but it can be hard for us to believe this when we are struggling with temptation. In spite of our struggles, however, God has declared that we are His children. Only repeated, willful sin can change that. When we learn to accept that God has accepted us in Jesus, we can move into a deeper walk with God.

Discussion: How does understanding our identity as Christians help us grow spiritually?
Source: Jesus, Son of God: Adult Teacher's Insights, page 63.