Churches need to offer the world a positive vision of sex, marriage and human sexuality, a Christian academic has said.

Glynn Harrison, who is also a psychiatrist, delivered the call on the final afternoon of the P Word Conference, hosted by Naked Truth Project, to address the problem of pornography in the Church and society.

"We are witnessing a profound recession of marriage across the Western world and it is hitting the poor the hardest," he said.

"The impact of family and stability on lone parents and most particularly children, I think that's one of the great social issues of our time."

He continued: "It goes almost entirely uncommented on or ignored in media. If we care about our kids as Christians and if we care about the poor, then we need to care about marriage."

Harrison proceeded to examine what needs to be done to "reverse decades of shame and denial in Christian culture" when addressing the subject of sex and human sexuality.

"We need to talk the talk, because we are people of the word of God," he suggested.

"Before we start talking about the Christian formation of our sexual identity, we need to talk much more about the bigger issue that sits behind it, the Christian vision of what it means to be made human."

In this culture of "radical individualism", Harrison said, the Church needs to find its voice to inform people of the "good news" that their life is not about them.

"It is the best news in the world. It is not about you, it is about the kingdom, an objective reality, a world of objective value, a world of love and relational reformation," he said.

The "A Better Story" author then put forward the importance of loving God first before other desires.

"This is the Augustinian teaching that you love God first and then you love everything else whether it's food, sex or beauty for the sake of God's kingdom and His glory," Harrison said.

"God first and our desires are to be formed through these reflections of His goodness, His love and His beauty.

"We need that radical vision of our bodies as being in formation as our appetites, as our longings, our desires are to be shaped toward God himself." 

He suggested people could be too easily satisfied as he recalled the words of CS Lewis who once observed that "the problem with pornography is not that our desires are too strong, but that they are too weak".

A radical new vision is required, Harrison said, to spur one another on to remember that appetites are "a foretaste, an appetiser of the contentment in Christ that is to come".

"That includes our deepest bodily desires for intimacy, for sex," he said.

"All of this is good in God's economy but it is still an appetiser, a pointer, to the marriage supper of the lamb when our deepest longings, our deepest desires for intimacy will be satisfied in a deeply mysterious way, but nevertheless a real way in Christ Himself."

Harrison's parting message with conference delegates was that all of this will need a "revolution" in the Church which he contended has too often focused on what salvation is while forgetting to "paint a vivid picture of what salvation is for, in this life as well as the next".

He added: "I guess in that respect we owe the sexual revolution our gratitude because it has shaken us from our complacency."