Consistent Calvinists, however — together with Holy Scripture — totally repudiate the Baptism of unbelievers, and of the infant children of unbelievers. They require the Baptism of adult believers — and of the infant children of such believers. Yet they affirm that God often regenerates and gives unlosable saving faith to covenantal fetuses long before their Baptism.
This pre-baptismal faith is bestowed before such infants might be sealed. Formerly, the seal was Circumcision. Since New Testament times, it is Baptism. Romans 4:11; Colossians 2:11-12; Ephesians 4:4,5,30.