Jon Voight, Angelina Jolie’s father, has backed her husband’s mother’s opposition to gay marriage.

Jane Pitt wrote to the Springfield News-Leader to say Christians should back Republican presidential candidate Mitt Romney, who is against abortion and same-sex marriage.

Mrs Pitt wrote: “Any Christian who does not vote or writes in a name is casting a vote for Romney’s opponent, Barack Hussein Obama – a man who sat in Jeremiah Wright’s church for years, did not hold a public ceremony to mark the National Day of Prayer, and is a liberal who supports the killing of unborn babies and same-sex marriage.”

Referring to Romney’s Mormon religion, she added: “Any Christian should spend much time in prayer before refusing to vote for a family man with high morals, business experience, who is against abortion, and shares Christian conviction concerning homosexuality just because he is a Mormon.”

It is understood she was responding to another letter-writer who said Christians should not back Romney on account of his faith.

The views she expressed, however, were at odds with those of her Hollywood superstar son, who has been an outspoken advocate for marriage equality, and his wife, but not, it now appears, his wife’s father.

Jon Voight told FOX411′s Pop Tarts column: ”Good for her!”

Pitt and Jolie dropped their pledge not to marry until every couple in the United States can do the same, gay or straight after facing pressure from their children to formalise their relationship.

A source said: “Jane has never wanted to talk politics with Angelina. She knew it would cause greater issues for them, and she wanted to try to have a relationship with the mother of her grandkids. She never thought her letter would be such a big deal.”