Credo Baptists frequently attempt to argue that infants are incapable of exercising faith. They conveniently forget that an 8-day-old was to have circumcision applied to him. If an 8-day-old cannot exercise faith, but was still administered the sign and seal of being in covenant with God, then why can an infant not receive baptism, the sign and seal of the new covenant?
Not only that, but according to Scripture infants can have faith. First of all, faith is a gift (Eph. 2:5, 8). Nowhere in Scripture does it say you have to be from a certain place or of a certain age to receive this gift or its benefits. Here are some passages that contradict the Credo Baptist's argument:
"Yet You are He who brought me forth from the womb; you made me trust when upon my mother's breasts. Upon You I was cast from birth; you have been my God from my mother's womb." Psalm 22:9-10"By You I have been sustained from my birth; you are He who took me from my mother's womb; my praise is continually of You. ... Do not cast me off in the time of old age; do not forsake me when my strength fails. ... O God, You have taught me from my youth, and I still declare Your wondrous deeds. And even when I am old and gray, O God, do not forsake me, until I declare Your strength to this generation, your power to all who are to come." Psalm 71:6, 9, 17-18"For he will be great in the sight of the Lord; and he will drink no wine or liquor, and he will be filled with the Holy Spirit while yet in his mother's womb. ... When Elizabeth heard Mary's greeting, the baby leaped in her womb; and Elizabeth was filled with the Holy Spirit." Luke 1:15, 41
Second, circumcision entered children into God's family of faith. They were under the umbrella of their parents' faith, whose responsibility it was to train them up and disciple them. Circumcision could only be applied to male infants. Baptism, however, is more inclusive.
Scripture does not say one way or the other whether there were infants/children present or not in the passages concerning Lydia, Cornelius, Stephanas, and the Philippian jailer. However, the Greek is singular when speaking of the individual believing, yet plural when speaking of the household being baptized. Furthermore, it is a safe bet that these households did consist of infants/children.
With regard to the above passages, I have no doubt that some people will attempt to argue against the first one based on it being prophetic of the Lord Jesus. Their argument will exclude everyone else and say that it only applies to Jesus, as He was God in the flesh. With the third one, John was filled with the Spirit from birth. Ergo, he had to possess the gift of faith. If there were no faith present, then how could he be filled with the Spirit? Does the Spirit now indwell those without faith?
God made specific promises, and there is nothing in Scripture that limits the place or the age for receiving these benefits. Since faith is a gift, God can bestow it upon His children at any point (unless you want to put God inside a box, and/or think that you are God).
If you think I have a dislike of Credo Baptists, or that I think some sort of ill about them, I encourage you to read my previous article, Paedo or Credo: Does It Really Matter?