Tertullian on Baptism

In preparing for Sunday I came across the link above to a comment Tertullian made on baptism.  He is replying to objections that Baptism is not necessary.  One objection to the necessity of Baptism is that Abraham found favor with God by faith apart from baptism and as such it is not necessary.  Tertullian provides a good description of how scripture and revelation are being constructed so that what is first is the beginning of the composition, not the fullness thereof. 

I appreciate this quote:   "Grant that, in days gone by, there was salvation by means of bare faith, before the passion and resurrection of the Lord. But now that faith has been enlarged, and is become a faith which believes in His nativity, passion, and resurrection, there has been an amplification added to the sacrament, the sealing act of baptism; the clothing, in some sense, of the faith which before was bare, and which cannot exist now without its proper law."

I wonder can we speak of simple and yet enlarging faith, or are these notions contradictory?