How do miracles serve as a sign that the word spoken is from God?

Although discernment is needed to distinguish deceitful signs from those that are from God, miracles testify to the reality of the spiritual realm, and ultimately to the truth revealed by God. When Aaron’s rod became a serpent before Pharaoh, the magicians of Egypt imitated the sign by their secret arts, “but Aaron’s rod swallowed up their rods” (Exo 7:9–12); and when the counterfeit failed, even “the magicians said to Pharaoh, ‘This is the finger of God’”, though Pharaoh’s heart was hardened (Exo 8:19).

Bearing this in mind, whoever performs true miracles works by the power of God, as the Lord himself testifies: when some said, “He casts out demons by Beelzebul, the prince of demons,” Jesus answered: “if I cast out demons by Beelzebul, by whom do your sons cast them out?… But if it is by the finger of God that I cast out demons, then the kingdom of God has come upon you” (Luk 11:15–20).

Consequently, such a person is in favor with God and a partaker of the divine Spirit; and when such a one speaks in God’s name, as did Moses and Aaron, we are assured that the Word of God is truly being proclaimed (Deu 18:21–22; Heb 2:3–4).

On this account, our Lord Jesus Christ himself presents his miracles as a powerful testimony to his divine mission: “the works which the Father has given me to accomplish, the very works that I do, they bear witness about me, that the Father has sent me” (Joh 5:36); and to the imprisoned Forerunner he answered: “Go and tell John about the things you hear and see: the blind receive their sight, the lame walk, the lepers are cleansed, the deaf hear, the dead are raised up and the poor have Good News preached to them. Blessed is he who finds no occasion for stumbling in me” (Mat 11:2–6).