What does the Bible say about the power of Christ's word?

In Luke 4, the people were astonished by Christ's doctrine because His word was with power and authority. This power is not merely in the spoken word but in its efficacious nature; when Christ commands, things happen exactly as He intends. For instance, in Genesis, God spoke creation into existence with simple commands like 'Let there be light,' demonstrating that His word not only holds authority but also has the power to effect change and create reality. This is further echoed in the New Testament where His word casts out demons and heals the sick, signifying an intrinsic potency rooted in the divine nature of Christ.