In the Federal Vision discussion at De Regno Christi, Peter Leithart made the following succinct comment about Federal Vision teaching:
The FV claim is: If the visible church is the body and kingdom of Christ, and baptism is the entry rite into the visible church, then baptism joins the baptized to the body of Christ and makes him or her a subject of His kingdom. Baptism makes the baptized a member of the more-than-human community of the church; baptism makes the baptized a member of the body of Christ, which really is the body of Christ, that is to say, the human community joined to the Incarnate Son through the Spirit.
This is consistent with the Federal Vision's emphasis on the objective character of the church and with its program to cast nearly every aspect of salvation in objective terms. My fear in such an approach is that it will create Christian nominalism, a people who "honors Me with their lips" (objective) but whose "hearts are far from Me" (subjective).