In a veiled criticism of same-sex marriage, Pastor Rick Warren of Saddleback Church says marriage has a "God-designed function" that celebrates the connection between a man and a woman.

"Whether or not you get married, if you're a woman, you need men in your life. If you're a man, you need women in your life," Warren writes on his website.

"Why? Because nobody holds the full image of God. Women get part of it, men get part of it, and we need each other. God wired it this way. God thought up gender. God thought up sex. And God thought up marriage. What a God!"

Warren then asks people if they ever wonder why God created man first and woman a bit later, and why He didn't just make them both at the same time.

The pastor suspects that God did it for Adam's benefit, because he wanted Adam to come to the realisation that he needed a woman in his life.

"You need companions in all different areas of your life. But there is nothing like the companionship of a marriage. It is in a relational class all by itself," says Warren.

He then shares the Bible passage Mark 10:6-9. It reads, "God made them male and female' from the beginning of creation. This explains why a man leaves his father and mother and is joined to his wife, and the two are united into one. Since they are no longer two but one, let no one split apart what God has joined together."

Warren explains that the passage proves that marriage is God's plan, and it's a tradition that people cannot simply disregard. At the same time, it dictates that marriage is solely between a man and a woman, and there's a reason why their body parts fit together.

Lastly, Warren says that marriage should be permanent.

"It seems like most people don't believe those statements any more. But it's still the truth!" he says. "It's still the way God designed marriage. And just because we live in the real, not necessarily the ideal, world doesn't mean we get to say the ideal doesn't exist."