From the Wisconsin Evangelical Lutheran Synod's "Doctrinal Statement on the Antichrist" cited by Green and linked here:
Since Scripture teaches that the Antichrist would be revealed and gives the marks by which the Antichrist is to be recognized, and since this prophecy has been clearly fulfilled in the history and development of the Roman Papacy, it is Scripture which reveals that the Papacy is the Antichrist.
This is not the first time this has come up, Green notes. Here's Bachmann responding to a similar story in a 2006 debate:
Pat Kessler, WCCO (debate moderator): We'll start with Senator Bachmann. Religion and politics that has crept into this campaign over and over again. The Minneapolis-based Star Tribune reports today, Senator, that the church you belong to is affiliated with the Wisconsin Evangelical Lutheran Synod, which, it says, regards the Roman Catholic pope as the Anti-Christ. Is this true, do you share the views of your church, and why should any Catholic in the Sixth District vote for you if it is true?
Bachmann: Well that's a false statement that was made, and I spoke with my pastor earlier today about that as well, and he was absolutely appalled that someone would put that out. It's abhorrent, it's religious bigotry. I love Catholics, I'm a Christian, and my church does not believe that the Pope is the Anti-Christ, that's absolutely false.
A spokesperson for the synod told Green that Bachmann is no longer a member of Salem Evangelical, having taken "the unusual step of formally requesting that release in writing" more than a year ago.
Read the whole story -- including the history of the synod and other Lutherans' take on it -- here.