The effects of original sin in man are a) death with all its temporal and eternal punishments and b) the manifold actual sins, of which each human being, being born in sin, is guilty.
Original sin entails, first of all, spiritual death, or the alienation of sinful man from the holy God, Eph. 2, 1. 5. 12. Unless spiritual death is removed through conversion, temporal death, Ps. 90, 7-9, which is a direct punishment of the first transgression, Gen. 2, 17, is followed by eternal death, or endless damnation, Matt. 25, 41; 2 Thess. 1, 9. The divine injunction "In the day that thou eatest thereof thou shalt surely die," Gen. 2, 17, was literally fulfilled, since spiritual death followed immediately upon the transgression, and our first parents were at once subject to temporal and eternal death.
The answer to the question how the eating of the fruit of the forbidden tree could produce results so dreadful is given by Scripture itself. The disastrous consequences of the first transgression were due not to any poisonous substance in the fruit itself nor to the fact that the devil had taken possession of the tree, but devolved upon Adam and Eve because in eating of the forbidden fruit, they transgressed the divine commandment, Gen. 2, 17. If it is further asked why God did not make another commandment the test of man's obedience, the Lutheran theologian Brenz replies: "Since the Moral Law was already written in man's heart, it pleased God to try his (man's) faith by a commandment not already made known to him." However, it must not be forgotten that all these questions in the last analysis belong to the unsearchable judgments of God, which lie beyond the grasp of human reason.
Original sin is the source of all actual transgressions, so that all actual sin comes from within man, Mark 7, 21-23; Ps. 51, 3-5; for since the fountain has been polluted, the waters flowing from it are likewise unclean. Because God is not the author of sin, but hates and condemns it, Ps. 11, 5; 5, 4. 5, His wrath and just punishments rest upon guilty man, Rom. 3, 19, both on account of his original sin and his actual sins, Eph. 2, 3; Rom. 5, 18.