People can choose their religion, but bigots can still discriominate against them based on their heritage. As an extreme example, in Nazi Germany, agnostics from Jewish families were sent to concentration ccamps along with Orthodox Jews.<quoted text>
Obama can't "choose" his race, Dum Dum, which makes racism far worse an offense than castigating someone over their chosen religion.
Romney can gain all sorts of credibility by becoming an atheist anytime he likes.
You can "choose" to worship false sky gods and wear magic underpants and look like a silly child, or be an adult and drop the phony religious dogma.
People can't "switch on and off" their race or their sexual orientation.
A more current example would be President Obama, who was raised as an agnostic and is now a Christian but is called a Muslim by bigoted kooks because his father was a Muslim.
If Romney wants to gain credibility by rejecting false beliefs, he should remain a Mormon but quit being a Republican.