The alarm was sounded in the final message of a synod of bishops from around the world who met at the Vatican on the theme of the "New Evagelisation", or the need to stop the hemorrhaging of the faithful, particularly in developed countries.
"Everywhere indeed we feel the need to revive a faith that risks eclipse in cultural contexts that hinders its taking root in persons and its presence in society ...," the message said.
The 1.2 billion-member Church will have its work cut out for it in developed nations in order to win back "the often distracted and confused hearts and minds of the men and women of our times", it said.
The Church is suffering desertions from its practicing flock in former strongholds in Europe, North America and Latin America due to sex abuse scandals, increasing secularism, rival faiths and open dissent against Church teachings on homosexuality and its ban on a female priesthood.
The message, a synthesis of the topics discussed in three weeks by more than 260 bishops, said that while the gospel could not be "a product to be placed in the market of religions", the Church needed to find new ways of putting it "into practice in today's circumstances".
It took a dig at the United States and Canada, saying the countries of North America needed "recognize the many expressions of the present culture in the countries of your world which are today far from the Gospel".
SEX ABUSE SCANDALS
While the 10-page message tried to convey optimism, the synod was dotted with examples of the hurdles the Church faces in its attempt to re-evangelize people in countries that were once a bedrock of the faith.
During the synod, some bishops said it had become more difficult to ask lapsed and lukewarm Catholics to return to the Church after the sexual abuse scandals that hit the worldwide institution in the past decade.
"We are believers ... we believe that the spirit of the Lord still is the principle of the source of whatever healing should happen," Archbishop Luis Antonio Tagle of Manila told a news conference presenting the message when asked about the sexual abuse crisis.
"This optimism is not in order to lead us to a false sense of serenity but really to drive us to find ways in addressing those really painful and scandalizing moments in the Church," said Tagle, who is one of six prelates who will be elevated to the high rank of cardinal next month.
Abuse scandals have been one of the greatest challenges faced by the Catholic Church, undermining its status as a moral arbiter and forcing it to pay hundreds of millions of dollars in compensation worldwide.
When the synod opened three weeks ago the pope acknowledged there were "bad fish" in the Church but urged lapsed Catholics to rediscover their faith and stop the advance of what he called a "spiritual decertification" in the developed world.
The synod formally ended on Sunday when the pope celebrated Mass with the bishops in St Peter's Square.