I don't know how a baby makes "a pledge of a good conscience toward God" in water baptism. And it's impossible for someone to make that pledge for you. My infant baptism did not relieve me of the responsibility to obey the Lord in water baptism and make a pledge of a good conscience after I believed in God as an adult. My infant baptism counted for nothing.
when the grows he is taught the faith then when child reaches the age of reason he is confirmed in the faith and makes the act of faith
Infants were not excluded from the mosaic covenant why would you exclude them from the new covenant?