PROVO — Days after Mitt Romney attacked secularism in a major speech on his Mormon faith, students at the presidential candidate's alma mater were encouraged to prepare themselves for battle against secularists.

Brigham Young University students must gather the intellectual and moral resources to combat abortion, same-sex marriage and moral relativity, Oxford University philosophy professor Daniel Robinson said Monday before a capacity crowd of more than 200 in the Lee Library Auditorium.

"It's important you recognize the burden you have on you," Robinson said. "You must be informed. Adversaries of everything you stand for are often informed, often passionate."

Not a member of The Church of Jesus Christ of Latter-day Saints, which owns BYU, Robinson has twice taught a semester as a visiting professor at the university, which he called "an estimable institution, for which the nation has every reason to be grateful."

"One need not be defensive about one's faith," Robinson said. "One need not be defensive about what one is trying to bring about in the world. What one is trying to bring about is a world in which children are educated, not raped, in which they go on the Internet to learn things that would be difficult to uncover even in the Library of Congress, not to be exposed to obscenity, pornography, things that corrupt and astound and numb the senses and render the most intimate associations in life merely carnal.

"This is what you're fighting, and you better fight it hard enough and with the intellectual and moral resources required by that fight, so that your children have a world that one doesn't hope to leave early, do you see, because it is so disgusting and depraved and defocused."

Robinson is among dozens of scholars who signed a 32-page proclamation supporting marriage created by a thinktank called the Witherspoon Institute. Others who have signed "Marriage and the Public Good: Ten Principles" include BYU law professors Richard Wilkins and Lynn Wardle, noted critics of the same-sex marriage movement.

Two other signatories have spoken at BYU. James Q. Wilson, a public policy expert at Pepperdine, delivered the inaugural Marjorie Pay Hinckley Chair of Social Work lecture in February 2005. Wilson described the negative effects of cohabitation and said it deserved more attention than same-sex marriage. Jean Bethke Elshtain, a social and political ethicist at the University of Chicago, first spoke at BYU in 1996 and defended her pro-life stance at a University Forum in October 2006.

Robinson said he is anxious for college students of faith.

"It isn't enough to have the right sentiments," he said. "It isn't even enough to have the right scripture. You have to have the right argument, because you will face those who think nothing of your scripture. You cannot win an argument by waving a book at someone. You understand that. You must prepare yourselves."