A.T. Robertson Commentary Romans 8:13

"for if ye live after the flesh, ye must die; but if by the Spirit ye put to death the deeds of the body, ye shall live." — Romans 8:13 (ASV)

Ye must die (μελλετε αποθνησκειν). Present indicative of μελλω, to be about to do and present active infinitive of αποθνησκω, to die. "Ye are on the point of dying." Eternal death.

By the spirit (πνευματ). Holy Spirit, instrumental case.

Ye shall live (ζησεσθε). Future active indicative of ζαω. Eternal life.