The Muslim grand mufti and Catholic archbishop led the interfaith church service at Sydney's Mary Cathedral, urging unity and condemning the hatred that led the killer to commit such a 'despicable' attack.
Welcoming the followers of all faiths at the service, the pair also acknowledged the show of support from politicians.
The list of MPs included Prime Minister Scott Morrison, Labor's foreign affairs spokeswoman Tanya Plibersek, NSW Governor David Hurley, NSW Premier Gladys Berejiklian, Opposition Leader Michael Daley, Opposition education spokesman Jihad Dib and Sydney lord mayor Clover Moore.
Archbishop Anthony Fisher opened the service, saying religious leaders have come together in a stand against "the real evil we have witnessed".
"We stand together in our horror at the real evil we have witnessed, at the violence perpetrated and the hate that inspired it," Dr Fisher told the congregation.
He said the actions, hatred and racism of the alleged shooter Brenton Tarrant have shown him to be "the enemy of mankind", adding that strength is found in compassion, not hatred.
Archbishop Anthony Fisher embraces Grand Mufti Ibrahim Abu Mohammed. Source: Facebook/Dr Ibrahim Abu Mohammed
"To all young people like him we say today: if it is real strength you want, you will find it in compassion and mercy, not hate and violence."
He concluded his address with the Arabic phrase for peace be upon you: "As-salaam alaikum".
Dr Fisher then handed over to the Grand Mufti Ibrahim Abu Mohammed after kissing him on the cheek three times and shaking his hand.
Dr Mohammed delivered his address in Arabic, speaking without notes, a translator at his side.
Archbishop of Sydney Anthony Fisher (left) greets Prime Minister Scott Morrison and wife Jenny Morrison during an Interfaith gathering at St Mary's Cathedral. Source: AAP
He said the interfaith family ties had only grown stronger in the wake of New Zealand's terror attack.
He said the actions of the alleged shooter would not "divide us".
"Whether you are Muslim or Christian or Jewish or any other faith group, as long as you live in Australia, as long as you are part of this family, nothing will divide us."
Earlier in the day, the prime minister gathered with about 200 parishioners at St Mark's Coptic Church in Arncliffe in southern Sydney with his wife Jenny Morrison and their two daughters.
The sails of the Opera House were lit up on Saturday night with the Silver Ferrn a day after Muslims were massacred while worshipping at mosques in Christchurch.
The Silver Fern of New Zealand is seen projected onto the sails of the Opera House in Sydney. Source: AAP
The alleged gunman's family approached NSW Police after viewing footage of the terror attack.
He posted a 74-page "manifesto" online before the attack, and a 17-minute video was also uploaded of him arming himself and entering a mosque where he started shooting.
"My understanding is the family (of this man) did approach NSW Police after the incident was on TV," NSW Police Commissioner Mick Fuller said in Sydney on Saturday.
Mr Fuller has asked people not to watch Tarrant's "disturbing" vision of the massacre circulating online.
NSW Police are conducting a "two-pronged investigation" which involves assisting New Zealand agencies and making sure the Australian terrorist "hasn't slipped through the cracks", Mr Fuller said.
He said there were "no active threats" in NSW linked to the shooting, however the national terrorism threat level remains at "probable".
The commissioner joined other senior police at an 80-strong meeting with religious leaders, including Grand Mufti Dr Ibrahim Abu Mohammed, at the Australian National Imams Council.
Police patrols and visits to mosques around Sydney's metropolitan area have been increased and will continue in the coming days and potentially weeks.
Additional reporting: AAP
