Sometime after the creation of Adam and Eve on the sixth day of creation, see Genesis 1:26-31, they rebelled against God by eating the fruit of the tree of the knowledge of good and evil.
“So when the woman saw that the tree was good for food, that it was pleasant to the eyes, and a tree desirable to make one wise, she took of its fruit and ate. She also gave to her husband with her, and he ate.” Genesis 3:6.
Psalm 91 is one of sixteen Psalms that are called Messianic Psalms; they are prophetic Psalms revealing the Messiah (Christ) to come. Psalms 2, 8, and 22 are three that you may know.
All but three of these Messianic psalms are quoted in the New Testament. These three psalms are Psalm 24, 72, and 89. The entire list of sixteen is as follows: Psalm 2, 8, 16, 22, 24, 40, 41, 45, 68, 69, 72, 89, 91, 102, 110, and 118.
Psalm 91 is one of sixteen Psalms that are called Messianic Psalms; they are prophetic Psalms revealing the Messiah (Christ) to come. Psalms 2, 8, and 22 are three that you may know.
When God confronted Adam and Eve after their sin in the Garden of Eden, see Genesis 3:1-24, He pronounced a series of curses and punishments; within this God made reference to the coming Christ who was to take away the sin of the world.