A girl whose mother is a lesbian has rallied against gay marriage after finding God.

After American woman Heather Barwick’s father walked out of her life when she was just a toddler, Barwick was raised by her mother and her female partner.

Hearing Barwick’s story, most people would assume her to be a women who supports the right of same sex people to get married.

But in a surprising twist, Barwick has recently come out as an opponent of marriage equality.

Heather Barwick.

In a heartfelt letter, published by The Federalist, Barwick said the absence of her father was deeply damaging – and children should not be without parents of both sexes.

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“I’m writing to you because I’m letting myself out of the closet: I don’t support gay marriage. But it might not be for the reasons that you think. It’s not because you’re gay. I love you, so much. It’s because of the nature of the same-sex relationship itself,” she wrote in a letter published by The Federalist.

“Same-sex marriage and parenting withholds either a mother or father from a child while telling him or her that it doesn’t matter. That it’s all the same. But it’s not. A lot of us, a lot of your kids, are hurting. My father’s absence created a huge hole in me, and I ached every day for a dad. I loved my mum’s partner, but another mum could never have replaced the father I lost.”

Barwick was raised by two women, but rejects same-sex parents.

Ms Barwick said she only realised the beauty of traditional marriage upon the birth of her own children.

She said she  let go of the pain her father leaving caused after she “came to Christ” and “felt that burden lifted off me.”

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Ms Barwick is facing Twitter backlash for her comments, as many believe her position should not be focused on same sex relationships, but on the breakdown of her parents’ relationship.

Others are doubting her newfound Christianity.

However, others are praising Ms Barwick for expressing her views.

Ms Barwick also signed a letter supporting controversial fashion duo, Dolce and Gabbana, and t heir recent comments about IVF children.