BRATISLAVA, Slovakia — Stanislav Zvolensky, the Roman Catholic archbishop of the Slovak capital here, was thrilled when he was invited to Brussels three years ago to discuss the fight against poverty with the insistently secular bureaucracy of the European Union.

“They let me in wearing my cross,” the archbishop recalled.

It therefore came as a rude surprise when, late last year, the National Bank of Slovakia announced that the European Commission, the union’s executive arm, had ordered it to remove halos and crosses from special commemorative euro coins due to be minted this summer.

The coins, designed by a local artist, were intended to celebrate the 1,150th anniversary of Christianity’s arrival in Slovak lands but have instead become tokens of the faith’s retreat from contemporary Europe. They featured two evangelizing Byzantine monks, Cyril and Methodius, their heads crowned by halos and one’s robe decorated with crosses, which fell foul of European diversity rules that ban any tilt toward a single faith.

“There is a movement in the European Union that wants total religious neutrality and can’t accept our Christian traditions,” said Archbishop Zvolensky, bemoaning what he sees as rising a tide of militant secularism at a time when Europe is struggling to forge a common identity.