Cardinal Francis Arinze told attendees at a eucharistic congress Charlotte, N.C., that "religion is not an option. It is not an accessory footnote.

It is the duty of the human creature in front of God the Creator."

Arinze spoke about the importance of Sunday Mass and the observance of Sunday as the Lord's day in an increasingly secularized world.

"Sunday is the Lord's day, the day of Christ, the day of the Church and also God's gift to us humans," said the Nigerian cardinal.

"It is important to see Sunday as source, summit and centre of Catholic life," he said.