Since, then, Christ died for us, why must we also die?

Heidelberg Catechism

Question 42. Since, then, Christ died for us, why must we also die?

Answer. Our death is not a satisfaction for our sin, but only a dying to sin and an entering into eternal life.[1]

[1] Jn 5:24; Rom 7:24-25; Php 1:21-23; 1 Thes 5:9-10