First, if we seek God’s fatherly mercy and kindly heart, we should turn our eyes to Christ, on whom alone God’s Spirit rests [cf. Matt. 3:17]. If we seek salvation, life, and the immortality of the Heavenly Kingdom, then there is no other to whom we may flee, seeing that he alone is the fountain of life, the anchor of salvation, and the heir of the Kingdom of Heaven. Now what is the purpose of election but that we, adopted as sons by our Heavenly Father, may obtain salvation and immortality by his favor? No matter how much you toss it about and mull it over, you will discover that its final bounds still extend no farther.
Accordingly, those whom God has adopted as his sons are said to have been chosen not in themselves but in his Christ [Eph. 1:4]; for unless he could love them in him, he could not honor them with the inheritance of his Kingdom if they had not previously become partakers of him. But if we have been chosen in him, we shall not find assurance of our election in ourselves; and not even in God the Father, if we conceive him as severed from his Son. Christ, then, is the mirror wherein we must, and without self-deception may, contemplate our own election. For since it is into his body the Father has destined those to be engrafted whom he has willed from eternity to be his own, that he may hold as sons all whom he acknowledges to be among his members, we have a sufficiently clear and firm testimony that we have been inscribed in the book of life [cf. Rev. 21:27] if we are in communion with Christ.
Institutes of the Christian Religion, III.xxiv.5