"Marriage can only be between a man and a woman," Rick Warren told an audience at the Vatican yesterday.

Speaking before Pope Francis' Humanum conference in Rome, the bestselling author and pastor of Saddleback church in California passionately defended traditional marriage.

"The Bible says you are to honour marriage. Sadly, today we all know marriage is dishonoured by a lot of people. It's dismissed as archaic, man-made tradition. It's denounced as an enemy of women...it's demeaned in movies and television and it's delayed out of fear that it will limit one's personal freedom. So today instead of being honoured, marriage is ridiculed, resented, rejected and redefined," he said.

"What are we going to do about this? The Church cannot cower in silence...the stakes are too high."

Warren argued that God reveals his presence and his character through marriage, that gender ideology "confuses our identity and destroys our dignity" and that the covenant of marriage and the act of sex parallel an intimate relationship with God.

He therefore stressed the importance of following Jesus' teaching on marriage, rather than bowing to "fads, feelings, opinions or political correctness".

"We build our lives on the unchanging truth of God's Word," Warren said. "You see, truth, is still truth, no matter how many people doubt it. I may deny the law of gravity, but it doesn't change gravity. And just because we break God's laws, does not invalidate them."

"A lie doesn't become a truth and wrong doesn't become right and evil doesn't become good just because it's popular. Truth is truth," he added.

Warren encouraged those gathered to celebrate healthy marriages; "We have to be a proponent of what's right, not just an opponent of what's wrong," he said. "Celebrating and highlighting and honouring marriage, I believe, is the best defence, when you show people what's real."

He also insisted that Christians should "face attackers with joy and winsomeness".

"Yes there's a raging cultural battle, but the Bible says we don't use the weapons of this world, and you overcome evil with good; bless those who curse you. These attackers are not the enemy, they are the mission field – they are people that Jesus shed his precious blood for," he said.

However, the crux of his message was that the Church must remain strong in its values, and continue to uphold the traditional teaching of marriage and the male-female relationship, despite cultural pressures. It should lead the crowd, not follow it, he insisted.

"The only way to always be relevant, is to be eternal," Warren said. "No revolution will last, including the sexual revolution...every lie eventually crumbles under its own deception. Cultures rise and fall, they come and go, but the word of God and the Church of God continues. What I'm saying is it isn't necessary to be on the side of culture – it's not even necessary to be on the right side of history, it's just important to be on the right side.

"History shows the majority is often wrong, remember Hitler? The dustbins of history are stuffed with conventional wisdom of cultures that proved false, and truth is not decided by a popularity contest."

Concluding his talk, Warren pointed to Ephesians chapter five, where marriage is described as a reflection of Christ's love for the Church.

"This is the deepest meaning of marriage. This is the most profound purpose of marriage, and this is the strongest reason why marriage can only be between a man and a woman," he said.

"There is no other relationship, including the parent-child relationship, that can picture this intimate union. To redefine marriage would destroy the picture that God intends for marriage to portray, and we cannot cave on this issue. It's a picture of Christ and his Church."

He finished: "Never give up, and never give in. The Church cannot be salt and light in a crumbling culture if we cave into the sexual revolution, and if we fail to provide a counter-cultural witness. It is a total myth that we must compromise and give up on biblical truth and marriage in order to evangelise.

"In the end, we have to be merciful to the fallen, we have to show grace to the struggling, we have to be patient to the doubting, but when God's word is clear, we must not, we cannot, back up, back down, back off, backslide or just give in.

"The Church must never be captivated by culture, manipulated by critics, motivated by applause, frustrated by problems, debilitated by distractions or intimidated by evil. We must keep running the race with our eye on the goal, not on those shouting from the side line. We must be Spirit-led, purpose-driven and mission-focused, so that we cannot be bought, we will not be compromised, we shall not quit until we finish the race."

Hosted by Church officials, the Humanum conference is titled 'An International Interreligious Colloquium on The Complementarity of Man and Woman'. It is expected to clarify the Vatican's stance on some of the issues that came out of the recent Synod on the Family, which caused some speculation that the Catholic Church was softening its approach to homosexuality and divorce.

It has welcomed around 30 speakers from 23 countries, and ends today.