Unionism no longer has a veto over Irish unity, Sinn Fein Assemblyman Gerry Kelly has said.
He was addressing a gathering of supporters in the New Lodge area of north Belfast to remember the 1916 Easter Rising.
"While Orangeism may remain, the spectre of the Orange state has gone, never to return," he said.
Mr Kelly was speaking ahead of the May 8th date for sharing power between Ian Paisley's Democratic Unionists (DUP) and Sinn Fein approaches.
A group of DUP councillors, led by the party's European representative Jim Allister have resigned in protest at the speed of the move to share power.
Mr Kelly added: "Change is always difficult. When taken in the context of a conflict, change can be traumatic. "And this can be made even more difficult when there are those, both within sections of unionism and within the British political and military establishment, who still want to hold on to the old ways."
He added that republicans must engage with unionists. "We seek a united Ireland and we must convince unionists that we are implacably opposed to doing to them what was done to nationalists and republicans," he said.
Yesterday Stormont's Deputy First Minister-elect, Martin McGuinness claimed the countdown to a united Ireland is under way.
As Sinn Féin members took part in over 100 Easter Rising commemorations across Northern Ireland and in the Republic, Mr McGuinness told an event at Drumboe in Co Donegal that 2007 had been a big year for republicans who are shaping history once again.
The Mid-Ulster MP, who will jointly head the new Northern Ireland Executive when it is re-established on May 8th with the Democratic Unionist leader, the Reverend Ian Paisley, as First Minister, insisted Sinn Fein was ready for government.
And he also said the party's republicanism did not stop on the northern side of the Border, with it aiming to be in government in both parts of the island.
"As the process progresses, more people are recognising that we have now entered the end phase of our struggle," Mr McGuinness said. "I truly believe that we have begun the countdown to a united Ireland, and we are continuing to get that message out as widely as possible.
"But Sinn Fein is the only party with the courage to say it aloud, and encourage proper management of the transition. "Denying the obvious will serve no purpose, other than to give false hope to those wishing it were not so."
Mr McGuinness said, in recent times, other parties in the Irish Republic had been anxious to show their united Ireland credentials. But, while this was welcome, he said rhetorical republicanism at election time would fool nobody.
"If they are serious about their aspirations for a united Ireland, then I challenge them to join with us and with like-minded campaign groups, trade unions and other interested sections of our society to create an alliance for Irish unity," he said.
"The potential to progress an all-Ireland strategy for ensuring full implementation of the Good Friday Agreement is tremendous.
"Those who attempt to interpret our participation in implementing the Agreement as a dilution of our determination to achieve Irish unity and independence could not be more mistaken."
The Sinn Fein MP said that, as republicans entered the final lap in the journey towards a united Ireland, they must try to understand the anxieties of unionists for whom such change was a terrifying prospect.