The answer is: The heart

Matt 15:19; Mark 7:21

Sin’s origin nestled deep within the human heart speaks volumes about human nature itself. Importantly, in both Matthew 15:19 and Mark 7:21, the emphasis is on the inner life – often referred to as the “heart”, a term that seems to reference more than our physical organ. It signifies our thoughts, intentions, and moral compass.

What’s fascinating is that many cultures throughout history have similar views! For instance, the ancient Egyptians observed the heart’s significance during the weighing of souls, believing it held the truth about a person's deeds in life. Beyond just these ancient practices, literature across time describes how inherent flaws can ripple through our actions and relationships. Genesis echoes this with the story of Cain and Abel, as Cain's joyful reputation faded when jealousy consumed him, illustrating the tragic potential lurking within the heart.

Furthermore, this understanding challenges the traditional view of sin being merely an external force or following a list of not-to-dos. Instead, it posits that it's our attitudes and perceptions, our honesty or dishonesty, compassion or bitterness, that truly pave our way toward moral beauty. In the grandness of life, reflecting on our inner world could prove to be a call to growth and self-awareness that leads us back to healthy, meaningful relationships with others. It reminds us that every choice stems from that complex and incredibly powerful place—the heart.