Shorter Catechism Q. 13. Did our first parents continue in the estate wherein they were created? A. Our first parents, being left to the freedom of their own will, fell from the estate wherein they were created, by sinning against God.
Commentary: Adam and Eve were the first two human beings, and every other human being is descended from them. That is why the Catechism refers to “our first parents.” If we were to trace our family tree all the way back to the beginning, we all would trace it back to Adam and Eve. In other words, we are all related.
The first two human beings were created upright, with an inclination and desire to do good. They weren’t created neutral, tottering between good and evil, nor were they created with a sinful nature. Moreover, they had free will. They had the power to do what they wanted, and were not forced to think, will or act in a certain way by an outside force, by a creature (e.g. Satan), or by God.
Although Adam and Eve were made upright, they had the ability to become evil. They were mutable or changeable. That will not be the case in the new heavens and new earth. Although saints will have free will, they will have the grace of perfection, being confirmed in holiness and thus unable to sin or become sinful. But in the garden, God did not give Adam and Eve that kind of grace (or a further preserving grace) but left them to the freedom of their own will. Hence, they could, and they did fall from their created state by sinning against God.