A proud grandson has described how his grandmother walked out of her church after an anti-LGBT sermon.

The American Reddit user, registered as BMMiller10, posted on the site that his grandmother had changed her conservative attitudes to homosexuality after he came out to her the previous year.

And after her pastor singled out another gay teenager in front of an entire congregation, promising to ‘address the problem of homosexuality’, she apologized to the teen and walked out.

She said: ‘There are a lot of problems here, and him being gay is not one of them.’

Since then the grandmother has left the church, apparently to the ire of the anti-LGBT pastor.

The user said: ‘It’s a small thing, and I’m not the best storyteller, but I’m so proud of her, and I thought I’d share.’

The user’s heartfelt story rocketed to the top of the LGBT Reddit bulletin board in recent days, while comments praising the grandmother’s bravery have poured in.

One comment said: ‘I can only imagine the amount of distress the kid had to go through experiencing that, but at least your grandmother hopefully softened the blow by making a stand like that.’

Another read: ‘I don’t think it’s a small thing at all. It’s a very big thing. I love her and I’m proud of her for standing up for herself, and you, and the boy at church. And for me too, even though she might not have known it.’