Nihil obstat is an LOOK AT ME!!!! official approval by a delegated censor of the Roman Catholic Church to publish a work dealing with faith or morals. It signifies that the publication is free from Catholic doctrinal or moral error. Catholic Church redirects here. ...
The phrase is Latin, meaning, "nothing hinders" or "nothing stands in the way." Latin is an ancient Indo-European language originally spoken in the region around Rome called Latium. ...
The Nihil obstat, along with the Imprimi potest, forms part of the Catholic Imprimatur. Imprimi potest is an official approval by the religious superior (or their representative) of a Catholic religious order to publish a work. ... An Imprimatur is an official declaration from the hierarchy of the Roman Catholic Church that a literary or similar work is free from error in matters of Roman Catholic doctrine and morals, and hence acceptable reading for faithful Roman Catholics. ...
It was the Catholic Church that decided Sunday should be the day of worship for Christians, in honor of the Resurrection.
Catholicism and Fundamentalism, by Karl Keating, copyright 1988 by Ignatius Press, San Francisco, bearing the NihilObstat and Imprimatur of the Catholic Church, page 38.
So dear reader, you should no longer have any doubt that Sunday is the first day of week, and that nowhere in the Bible is Sunday blessed, sanctified or commanded by God as a day of weekly worship.