WATCH: Lyra McKee's powerful TedX talk that made her a 'hero' to many in LGBT community
Lyra McKee urged a "fight for the hearts and minds" of those who oppose same-sex relationships.
The murdered journalist said she was taught as a child by the church that she would go to hell because of her orientation.
Northern Ireland is the only part of the UK or Ireland where same-sex marriage is not allowed.
Ms McKee said: "We need to do the one thing that I didn't want to do when I left school at 16 - we need to have conversations, difficult conversations, and fight for the hearts and minds of those who oppose us."
She said she hated herself for much of her life because of what religion taught her about people like her.
"When I stopped hating myself I started hating religion."
She recalled in a TedX talk at Stormont: "The first lesson I learned about being gay was that it was evil and I was going to hell for it, I learned that from the Bible.
"There were times that I would cry in my bedroom as a teenager, bargaining with God, asking him not to send me to hell because I was so convinced that I was going there.
"This text, this Bible, for many people it offers them hope and salvation, but for me it offered a prison sentence, and I think it is the same for a lot of other LGBT young people."
The journalist was a "hero" to many in the LGBT community, advocacy workers said.
John O'Doherty, director of the Rainbow Project, said she had a huge impact on many in Northern Ireland's LGBT community.
She supported people in coming out and used her own story to empower others to live as their most authentic selves, he added.
She volunteered and raised funds for the organisation with a Strictly Come Dancing event.
Mr O'Doherty said: "Lyra described herself as someone with two left feet - but like everything she did in her life, she gave it everything she had and our lasting memory will be of a smiling and dancing Lyra.
"To lose someone like Lyra at any age is a difficult thing to accept, but to lose her at 29 in such despicable and avoidable circumstances is devastating.
"Our thoughts today are with Lyra's family, partner, friends and everyone across Northern Ireland society who will be feeling this loss today.
"Violence to achieve political aims can never be justified and we hope that the perpetrator is brought swiftly to justice."
The death of an innocent civilian caught in the wrong place at the wrong time was one of her strongest memories of the conflict.
The journalist wrote about loyalist gunmen who sprayed a north Belfast pub with bullets at the start of 1998 as politicians were gearing up to sign the Good Friday Agreement.
She recalled the death and added: "He was an innocent civilian, caught in the wrong place at the wrong time."
She used a Belfast Telegraph newspaper piece to highlight the loss of people to suicide since the 1994 paramilitary ceasefires.
She recalled the revulsion expressed in August 1998 when dissident republicans killed 29 shoppers in Omagh in a bomb attack gone wrong.
It was the bloodiest atrocity of the conflict and Ms McKee said the majority had wanted the senseless violence to end.
The plight of the homeless was also a foremost concern for her.
Friend Ian Shanks said: "Lyra McKee was everything you wanted to be in life - honest, funny, sincere, caring.
"I remember how she always wanted to help with our homeless group, she always genuinely cared about everyone around her and beyond."