Baptized Heirs with Abraham (Gal. 3:27)

Many people in the church today think that baptism is merely a New Testament symbol demonstrating that the church is different from Israel. However, the Apostle Paul does not see such a distinction in the people of God. Is the church the replacement for Israel? Is the church something that is radically different from Israel? What does the sacrament of baptism have to do with Israel and the church?

Why One Baptism? (Ephesians 4:5 (LD 27; BC 34)

Our confession uses strong language that we are to be baptized once.  This means that we do not agree with other traditions that will baptize someone a second time because they do not see infant baptism as being a valid baptism.  Why do we believe in one baptism?  What is the bigger picture of this baptism?  How do we as Reformed people see baptism as something for children and adults?  Why are we not Roman Catholic even though we baptize infants?