Critics of Christianity often asked the question, “if Adam and Eve were perfect, how could they sin?” But, they make an error when they asked the question. First of all, the Bible does not say that Adam and Eve were perfect. It says that they were good (Genesis 1:31). But within their goodness was the ability to sin – which they did. Being good, as God created them, does not mean they are incapable of doing something wrong. Only God possesses the inability to do evil. Think about this. Whatever attribute God possesses, He does not possess its opposite. So He alone is holy (1 Pet. 1:16). It is part of His nature. Biblically speaking, God cannot violate His own nature and lie (Titus 1:2). He cannot sin. This is a quality that belongs to God alone. We see this hinted at in the fact that there are elect angels (1 Tim. 5:21) who apparently were elected not to sin.
Second, what does it mean to be ‘perfect’ in the eyes of the questioner? What standard of perfection is there that the critic has by which he or she proposes the challenge to ask the question? Without the terms being defined, the question is unclear. If he provides an answer, then we need to examine it according to the Scriptures to see if his definition is biblical. After all, he is asking the question from within the biblical perspective. So we would need a biblical definition of perfection in order to apply it to Adam and Eve. If he cannot provide that standard from Scripture, then how is the question valid?
Furthermore, God alone is “perfect.” He alone has infinite knowledge and wisdom. But, these cannot be conveyed to Adam and Eve since they are not God. This is why God gave the command not to eat from the fruit of the tree of the knowledge of good and evil (Genesis 2:17). God’s knowledge and moral goodness, along with the consequence of violating that moral goodness, were symbolized in the placement of the trees, one that led to life and the other that led to death.
Having said all this, some critics of Christianity want logical and philosophical answers dealing with epistemology, justification of actions, the reason God did not intervene, and more. Though we can Provide various answers to those challenges, the account in Genesis is not meant to be a philosophically exhaustive elucidation of human free will as it relates to Eve’s ability to be deceived. The account in Genesis 3 demonstrates how the fall occurred in concert with the evil one who first doubted God’s word (Gen. 3:1) – which is something critics of Christianity do all the time. Whenever that occurs, deception follows.
So, it is not the case that Adam and Eve were perfect. They did not possess the quality of God’s perfection since God is the standard of what is perfect. They were creatures. Therefore, they were open to being deceived and falling into sin.