Religions face an existential challenge: how to remain eternally true while adapting to temporal change. Through the lens of Judaism's legal evolution from biblical to modern times, a fundamental pattern emerges - the delicate interweaving of divine unchangeable elements with human adaptable components. While religious authorities historically maintained claims to divine continuity through flexible oral law and creative interpretation, modern historical consciousness and scientific knowledge have rendered these traditional interpretive methods increasingly difficult to defend. Yet complete abandonment of legal structures threatens the very coherence of religious practice. Through comparative analysis of Orthodox, Reform, and Conservative approaches to religious authority and legal interpretation, this research reveals how Conservative Judaism offers a viable model for conscious evolution while preserving essential religious content. The findings demonstrate that sustainable religious practice requires clearly distinguishing between eternal elements - fundamental theological concepts and forms that transcend time - and temporal elements open to modification. Success depends on religious leadership's ability to balance preservation of core spiritual values with necessary adaptation, creating a "flexible halachic structure" that maintains authenticity while enabling measured change. This model provides insights for how religious traditions broadly can navigate between timeless truths and contemporary realities.