Our assurance, our glory, and the sole anchor of our salvation are that Christ the Son of God is ours

Our assurance, our glory, and the sole anchor of our salvation are that Christ the Son of God is ours, and we in turn are in him sons of God and heirs of the Kingdom of Heaven, called to the hope of eternal blessedness by God's grace, not by our worth.

John Calvin
Institutes of the Christian Religion 3.17.1