That saving faith (fides directa, fides actualis) is found not only in adults, but also in regenerate infants is proved in Scripture by the following: a) Scripture directly ascribes to such children saving faith, Matt. 18, 6; 1 John 2, 13; Ps. 8, 2; b) Scripture ascribes to them the fruit and effect of saving faith, namely, eternal life, Mark 10, 14. The example of John the Baptist, Luke 1, 41—44, who was filled with the Holy Ghost while yet in the womb of his mother, proves that children can believe before they have reached the years of discretion, though in this case the ordinary means of grace (the Word and the Sacraments) were not applied. If from this exceptional case the conclusion is drawn that it is not necessary for us to apply in every instance the means of grace to infants, we answer that God has indeed bound us to the use of these means, Mark 16, 15.16; Matt. 28, 19. 20, but that He Himself is not bound to them.
While it is impossible for us to describe in detail the faith of infants, we must hold that it is nevertheless an active trust in the divine promises of grace, or an active apprehension of the merits of Christ, Matt. 18, 6; Ps. 71, 6. Fides infantium fides actualis est, non habitus otiosus vel mera potentia. Gerhard rightly remarks: “We are not solicitous about the mode of this faith, but we simply acquiesce in the fact that infants really believe.” (Doctr . Theol., p. 549.)