Deuteronomy 18:21 (KJV) states, "And if thou say in thine heart, How shall we know the word which the Lord hath not spoken?"

This verse is part of a larger passage in Deuteronomy in which Moses is instructing the Israelites on how to discern between true prophets and false prophets. In the previous verses, Moses warns the people about the dangers of false prophets and how to distinguish between those who speak for the Lord and those who do not. In verse 21, he addresses the skepticism that may arise in the hearts of the people, questioning how they can be certain that the words being spoken are truly from the Lord.

The overall theme of Deuteronomy 18:21 is the importance of discernment and seeking after the truth. The verse speaks to the human tendency to doubt and question, particularly when it comes to matters of faith and spirituality. It acknowledges the natural skepticism that can arise when faced with the claims of a prophet or religious leader and offers guidance on how to navigate these uncertainties.

The context of this verse is important for understanding its significance. At the time of Moses, the Israelites were in the process of establishing themselves as a nation and were receiving guidance and laws from God through the prophet Moses. The Israelites were surrounded by various pagan cultures and false prophets who claimed to speak on behalf of deity. In this environment, it was crucial for the Israelites to be able to discern the true words of God from the deceitful words of false prophets.

The verse also reflects the broader theological principle of testing the spirits, which is a theme that appears in various places throughout the Bible. In 1 John 4:1, for example, believers are told to "test the spirits to see whether they are from God." This principle emphasizes the need for discernment and critical thinking when it comes to matters of faith and spirituality.

The symbolism in this verse lies in the metaphor of "knowing the word which the Lord hath not spoken." This metaphor speaks to the concept of spiritual discernment and the ability to distinguish between truth and falsehood. It implies a deep understanding of the nature of God and His will, as well as the ability to recognize when something does not align with His character and intentions.

In a broader sense, this verse can also be applied to the idea of seeking after truth and wisdom in all areas of life. The skepticism expressed in the verse reflects a healthy questioning and critical thinking, which are essential for personal growth and intellectual development.

Overall, Deuteronomy 18:21 offers a timeless lesson on the importance of discernment and critical thinking, particularly in matters of faith and spirituality. It encourages believers to test the claims of prophets and religious leaders and to seek after the truth with an open and discerning mind. The verse serves as a reminder that truth is something to be pursued and that skepticism, when handled with wisdom and humility, can lead to a deeper understanding of God's will and purpose.