Don’t become Muslim:

In general, being a Mormon is viewed as far less of a liability for a presidential candidate than not believing in God or being a Muslim. Roughly six-in-ten Americans (61%) say they would be less likely to vote for a candidate who does not believe in God, while 45% say they would be reluctant to vote for a Muslim. At the same time, more people express reservations about voting for a Mormon (25%) than about supporting a candidate who is an evangelical Christian (16%), a Jew (11%) or a Catholic (7%).

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Among Republican and Republican-leaning registered voters, Romney’s overall favorability rating, though high at 75%, is significantly lower than the favorability ratings of Giuliani (84%) and Thompson (88%), and roughly equal to the favorability rating for McCain (71%). Romney’s standing relative to the other candidates is particularly poor among those who say they would be less likely to vote for a Mormon; among this group, Romney’s favorable rating (54%) is substantially lower than those for Giuliani (76%), McCain (72%) and Thompson (82%).
Romney’s relative standing is much better among Republican and Republican-leaning voters who do not express reluctance about voting for a Mormon; indeed, among this group, Romney’s favorability rating (81%) is significantly better than McCain’s (71%), while somewhat lower than Giuliani’s (86%) and Thompson’s (90%).

Source: Pew.