Catholics in Scotland were yesterday warned that their faith was coming under attack from a rising tide of secularism.

Mario Conti, the Archbishop of Glasgow, urged his flock to resist threats to their way of life from everything from same-sex civil partnerships to anti-sectarian campaigners critical of denominational schooling.

The archbishop did so in a special sermon to mark the quarter century since the first ever papal visit to Scotland, by John Paul II in 1982.

He said: "At a distance of 25 years, we need to reflect on the Holy Father's words: In so many areas of life the most fundamental principles of our Christian life are not only questioned, but ridiculed and threatened with sanction.' "Individualism has come to predominate the growth of the quest for individual rights has taken precedence over what is right."

Archbishop Conti, speaking yesterday at Carfin Grotto in Lanarkshire, cited the "ever-increasing incidence of abortion and the creeping acceptance of euthanasia" and claimed that marriage was being downgraded by "equal rights being accorded to unmarried and same-sex unions".

He also spoke of "repeated attacks on our Catholic schools, unjustly accusing them of fostering sectarianism" and reinforced long-standing concerns among some Catholics that equality legislation would lead to faith-based adoption agencies being forced to place children in gay households.

The archbishop quoted at length in his sermon from John Paul's rallying cry to Catholics in Glasgow's Bellahouston Park on June 2, 1982.

Then the Pope said: "We find it harder to follow Christ today than appears to have been the case before. Witnessing to him in modern life means a daily contest.

"As believers we are constantly exposed to pressures by modern society, which would compel us to conform to the standards of this secular age, substitute new priorities, restrict our aspirations at the risk of compromising our Christian conscience.

"Things abhorred a generation ago are now inscribed in the statute books of society. These are issues of the utmost gravity to which a simple answer cannot be given; neither are they answered by being ignored.

"Matters of such magnitude demand the fullest attention of our Christian conscience."

Many of the hundreds of thousands who heard the Pope speak in 1982 were young.

John Paul II, in his sermon then, called them "the heirs to a sacred heritage. Your forefathers have handed on to you the only inheritance they really prized, our holy Catholic faith."

Now most are in their 40s and even 50s. Many are no longer part of the church, at least if recent figures are to be believed.

There were 296,000 church-going Catholics in Scotland in 1980. By 2005 that figure had dropped nearly 100,000, to 198,000, according to Christian Research.

The church remains, by attendance, the biggest in Scotland and those who did turn up for mass yesterday were given a pastoral letter from Scottish bishops commemorating Pope John Paul II's visit.

The church last week made an attempt to win back the young.

It launched a new learning pack designed to ensure that values taught in schools were credited to Christianity and called for Christian morals to be added to the new curriculum being planned in Scotland.

Secularists quickly retorted that the faith had no copyright on values.

Bishops in England yesterday also defended Catholic schools in a letter read out to congregations in all Catholic churches.

Earlier this year the NASUWT teaching union called for a blanket ban on any new state-funded single faith schools, saying they caused social divisions.