Final answer:
Sin entered the human race through Adam and Eve's disobedience to God in the Garden of Eden.
Step-by-step explanation:
In Christianity, sin is believed to have entered the human race through Adam and Eve's disobedience to God in the Garden of Eden. According to the biblical account in Genesis 3, God placed a tree called the 'Tree of Knowledge of Good and Evil' in the garden and commanded Adam and Eve not to eat its fruit. However, they were deceived by the serpent and ate from the tree, which resulted in the Fall of humankind and the introduction of sin into the world. This event is often referred to as the Original Sin.
As a consequence of Adam and Eve's disobedience, all humans are believed to inherit a sinful nature, leading to a separation from God and the need for redemption and salvation. The concept of sin and its impact on humanity is a central theme in Christian theology.