Poland's bishops have opened religious and political celebrations that mark 1,050 years of Christianity in Poland with a debate on its significance for the nation.

The church and the conservative government jointly organized the three-day ceremonies that opened Thursday in the western town of Gniezno, considered to be the cradle of Poland's Catholicism. Government members want the ceremonies to stress that Poland's Catholic identity ties the nation to Western culture and values, especially now when the European Union is criticizing its policies.

Pope Francis' envoy and President Andrzej Duda will attend a Mass later Thursday at Gniezno's 10th-century cathedral.

Duda will address a special session of lawmakers and senators on Friday.

Poland's Prince Mieszko I was baptized in Gniezno around the year 966, chroniclers say.