Beyond a Land Promise (Genesis 17:1-27; Acts 2:29-41)

The Lord makes a promise to Abraham about bringing about His kingdom through the champion line.  This promise is tied to a land and also to circumcision.  Why would we desire to appeal to this passage for infant baptism?  What does Genesis 17 tell us about the covenant and the covenant sign?  What is Peter saying regarding the application of the covenant promises to us?