The plight of persecuted religious believers overseas should inspire American Catholics and others to continue their defense of religious freedom at home, Archbishop William Lori of Baltimore said.

"What solidarity we should have with these believers. We should be inspired by their courage and renewed in our resolve not to let religious freedom in our country be compromised by degrees until it all but disappears from our society," the archbishop said.

"They are the ones who teach us about God's precious gift of religious freedom," he said in a June 21 homily. "No matter how great the threat to life and property, these believers exercise that God-given freedom which no tyrant can eradicate – the freedom to bear witness to one's faith even at the cost of one's life."

U.S. religious freedom challenges are not the same magnitude as outright persecution facing Christians in other countries, he said, but U.S. Christians are nevertheless "in the same boat."

Archbishop Lori's homily came during Mass at Baltimore's Basilica of the National Shrine of the Assumption of the Blessed Virgin Mary. About 1,000 people attended the Mass, which launched the U.S. bishops' third Fortnight for Freedom event.

Archbishop Lori heads the U.S. bishops' religious freedom committee.

"We seek the freedom to bear witness to Christ's love, not just in church but in our service to the wider community through works of justice and charity, education, social services, and health care," the archbishop said, echoing the 2015 campaign's theme "Freedom to Bear Witness."

The event, from June 21-July 4, coincides with the feasts of saints including Thomas More and John Fisher. It is intended to raise awareness about threats to religious freedom in the U.S. and about the need for religious freedom protections like the Religious Freedom Restoration Act.

The Fortnight for Freedom campaign began in 2012 in the wake of the Obama administration's efforts to mandate that employers provide insurance coverage for drugs and procedures to which they have religious and moral objections, such as sterilization procedures and contraceptive drugs, including drugs which have abortion-causing effects.

While the U.S. Supreme Court's 2014 ruling against the Obama administration mandate in favor of Hobby Lobby provided some protections for closely-held for-profit corporations and their owners, the federal courts are still considering legal challenges for non-profits and other groups.

The rise of "gay marriage" and strict application of anti-discrimination law have also caused problems for Catholics and other religious believers. Small businesses with moral reservations about participating in same-sex ceremonies have faced discrimination lawsuits for declining to provide services, while Catholic-run adoption agencies have been forced to close because the law would require them to place children with same-sex couples.

Archbishop Lori said religious freedom relates to "our most fundamental relationship, our relationship with God."

He said there are "many intolerant voices" working to stifle religious freedom by "labelling as bigotry long-held beliefs about the sanctity of life and marriage," by imposing "a grey and godless secularism," and by "branding basic religious liberty protections as 'a license to discriminate'."

"Increasingly religious institutions in the United States are in danger of losing their freedom to hire for mission and their freedom to defend the family," he said. "It is one thing for others to disagree with the Church's teaching but quite another to discriminate against the rights of believers to practice our faith, not just in word but in the way we conduct our daily life, ministry, and business."

Efforts to pass state-level religious freedom protections have faced increasing opposition from activist groups and large businesses. The controversy over Indiana's 2015 Religious Freedom Restoration Act was so intense that the Indiana legislature passed an amendment that critics said significantly undermined religious freedom in the state.

The activist group Catholics for Choice has launched a campaign to undermine the Fortnight for Freedom. It has placed ads in the front cover wraparound of the Washington Post Express showing a caricature of a bishop who points at the viewer and says "We want you to help us discriminate."

Catholics for Choice said the ad shows a Catholic bishop "recruiting an army of intolerance." It claimed the bishops want the "freedom to discriminate against anyone who disagrees with them."

Archbishop Lori in his homily praised the early Christians' courageous witness of faith amid persecution, as well as later saints like St. Thomas More, St. John Fisher and English and Irish martyrs. He cited the recent execution of 20 Coptic Christians and one companion in Libya, whom Islamic militants beheaded for being Christian.

He prayed that Catholics will "allow Christ to awaken our faith and to stir us into action so that we may preserve, protect, and defend our God-given freedom to bear him witness…may God bless us and keep us always in his love!"