Twenty-five years ago, Britain and Ireland signed the Good Friday Agreement, ending decades of bloodshed known as the Troubles. At the stroke of a pen, Northern Ireland became one of the world’s most ambitious experiments in how to reconcile a deeply divided society.

Even now, remnants of separation between Protestant and Catholic Northern Ireland linger: the barriers between neighborhoods known as peace walls; murals with images of Queen Elizabeth II or Irish republican heroes; the Union Jacks and Irish tricolors that flutter from lampposts.

But more and more, these are relics. As it commemorates a quarter-century of peace, Northern Ireland is searching for its place as part of both the United Kingdom and the island of Ireland, seeking to turn ancient divisions into a formula for future prosperity.

At the heart of the Good Friday Agreement is a commitment to preserve a political balance between unionists, most of them Protestant, who want Northern Ireland to remain part of the United Kingdom, and nationalists, most of them Catholic, who favor unification with the Republic of Ireland.

That is a challenge because for the first time, Catholics outnumber Protestants in Northern Ireland. The prospect that this could lead to a unification of Ireland has alarmed unionists, who seize on holidays and historical anniversaries to assert their religious identity. Nationalists, more confident of their future, celebrate their Irish identity at sporting events.

In the decades since the Troubles subsided, Northern Ireland has become like many Western countries — a secular society in which the younger generation has little time for the sectarian preoccupations of their parents and grandparents.

Whether in pubs or concert halls, young Protestants and Catholics tend to mix easily, united by the quest for fellowship and a good time. For them, the rainbow Pride flag is just as likely to hang from the ceiling as the Irish or British flags.