I think the quotation is spurious, even though I sympathize with its argument. According to Google Books, the first volume of Webster's Works does not contain the word "baptize". Webster called the United States a "nation" all the time, including in the speech cited (which does not contain the quotation). The purported quotation appears to originate with Mildred Rutherford, who cited "The Federalist", a work of Webster's that does not appear in the Library of Congress's catalogue. She seems to have fabricated it out of material borrowed from Albert Taylor Bledsoe's "The War Between the States". A search of Google Books will provide the texts.