I just heard a sermon about christian marriage and the pastor said that in a true christian marriage there's no room for the concept of divorce. I think he's right!
The only problem I see is that in order for a couple to have a "true Christian marriage", you would need two truly perfect people.
I was raised to believe pre-nups were completely wrong as well... However, I've seen many things throughout the years--including going to Christian schools for most of my schooling and seeing many Christian couples, such as pastors and teachers, divorce, and it was not pretty.
You don't know if your spouse is going to start having an eye for that younger person at work (that's what happened to me--when I was 25, my husband left for a 19-year-old), or a million other things that might happen. Long after he was gone, I found writings indicating that my ex had also been struggling with thoughts of wanting to lash out at me in physical violence. If that would have happened, I would have left him.
And I know you can't say, "Well what if..." about everything, but I do believe you also have to be prepared in life. Another problem in my marriage is that I was a saver and he was a spender, often racking up thousands of dollars in credit card bills behind my back. It's how he coped with stress, pain, etc. I'm just blessed that my credit history wasn't totally ruined when he divorced me, because I've seen that happen to other people. You really do have to be careful.
As I've written about before, I'm on two Christian dating sites and many of the older women who are widows talk about men who approach them, claiming to be smitten with them, saying they are the man God has for them... and in the same sentence, ask if their husband left them a house and inheritance.
People tell me I'm "young", but I can say that things are also very different for me at age 37 vs. when I was 25. My personal goal is to own everything I have and live debt-free--I would be very protective of that goal and lifestyle even if I got married again. I want to use anything I've saved for missions work, charities, supporting my old orphanage, etc.--not supporting an ex-husband and his new, younger catch. I think there is a very cautious balance between trusting someone... but also leaving yourself too vulnerable.
I don't see it as being materialistic--I personally see it as using your brain and being a good steward of God's blessings... Just my own opinion though.