Mr Turnbull told the congregation at St Mark Coptic Orthodox Church in Arncliffe that the Australian government and community stood with Coptic Christians to defy terrorists, following deadly attacks against them in Egypt earlier this year.
He went on to say how unlike in Egypt and other parts of the Eastern Mediterranean, Australia was stronger because of its diversity and because it maintained respect for differences.
Prime Minister Turnbull said that was the reason it was essential to toughen up the current citizenship legislation.
We make no apologies for reinforcing fundamental Australian values: PM
"We make no apologies for reinforcing the fundamental values of Australians and of Australian citizenship," Mr Turnbull said.
"We say that what we have done here is something of which we can all be proud. We say that what we have created is a remarkable nation. We say it is founded on Australian values which are right, they are good, they are eternal, they are strong."
"They are fundamentally committed to freedom, the rule of law, democracy, mutual respect, the equality of men and women."
"We all believe in that and we say that those who seek to come here and to be citizens in our country should subscribe to those values as well because they are ours and they are right."
Under the proposed citizenship changes, migrants would be asked to prove their commitment to Australia by passing a revised citizenship test, and a more stringent English language test.
They would also be asked to demonstrate they have integrated into the community, as well as face a longer wait before being able to apply for citizenship.
Mounting death toll from attacks on Coptic Christians
Last month, gunmen attacked a bus carrying Coptic Christians in central Egypt, killing at least 28 people.
In April, two blasts targeting Coptic Christians on Palm Sunday killed at least 44 people.
An explosion at St George's Coptic church in Tanta killed 27 people.
Hours later, a blast outside St Mark's Coptic church in Alexandria left 17 dead.
Labor criticises 'English test'
Mr Turnbull's comment come as Labor on the English language test component under the new citizenship laws.
In an interview with ABC TV Insiders program on Sunday, Labor Citizenship Minister Tony Burke criticised the government's citizenship legislation currently before parliament.
Mr Burke read an alleged extract from a sample of a proposed English test about Greek historian Herodotus, who lived in the 5th Century BC, about the Battle of Thermopylae.
"There is not a single person in Australia who would have to say you would have to do a comprehension test like that before you can pledge allegiance to this country," he told Insiders.
"That's exactly where Peter Dutton has taken us with a policy that was all about his idea of wedge politics - and had nothing to do with Australia."
In a press release on Wednesday, Mr Dutton "made no apologies" about the proposed English test.
"The citizenship legislation requires those seeking Australian citizenship to be competent in English," he said.
- with AAP
