Thank you for the Biblical question on not to shave the corners of the face, “Why does the Bible say not to shave the corners of the face?”
Leviticus 19 says this, “Do not cut the hair at the sides of your head or clip off the edges of your beard” (A searchable online Bible in over 150 versions and 50 languages). Bible citations are in the New International Version.
The Biblical text does not state the reason why God prohibited the Jewish men to cut the sides of their heads or clip the edges of their beards. It may seem strange to the reader why God would give such a prohibition.
One possible answer relates to Exodus 19 whereby God declared that he wanted the Jewish people to be a special set apart people for himself. The text says this, “Now if you obey me fully and keep my covenant, then out of all nations you will be my treasured possession. Although the whole earth is mine, 6 you will be for me a kingdom of priests and a holy nation.’ These are the words you are to speak to the Israelites” (NIV).
The prohibitions given to Jewish people were to make them a distinct people from the neighboring people and countries. Their appearances including their clothing will become a distinguishing mark as a Jew to other people groups. It’s an outward testimony that the person was a believer in the God of Israel, YHWH.
Today as one looks at people, there is nothing necessarily distinguishing between agnostics, atheists or Christian by their appearance. Perhaps a person wearing a religious symbol like a cross may indicate that the person is affiliated with the Christian faith. When one sees a person dressed in a robe in certain colors with beads around his neck and a shaved head, most people would identify that person as being a Buddhist just as one may identified a Muslim woman by her clothing and veil over her face. The appearance may reflect a person’s belief.
SUMMARY: The uncut beard by itself may not indicate that a person is a Jew, but are there other indications that one may be a Jew? One has to look more closely. There are other signs for an orthodox Jew, if I may use that description of them.
For more perspectives:
https://www.quora.com/Why-does-the-Bible-say-not-to-shave-the-corners-of-the-face