I think that nonCatholics can get married outside a church building (afterall, the Protestant churches I have seen are just a hall anyway). And of course, that marriage is still valid. But I would have thought it would be preferable to get married in a church, and I would have a serious talk with a Catholic who didn't want to get married in a church because of our theology about the Eucharist. I don't think that helen of britain (HI!) is saying that a marriage outside a church is not valid. Just that inside a church is preferable (right?).
Don't worry Heveans angel, dresses and a huge crowd do not make a marriage valid. Eve wasn't wearing anything, they were naked and knew no shame (Iwouldn't recommend this though, we now live in a fallen world
). A crowd is not necesary, but I do believe witnesses are. My brother and sister inlaw got married in the presence of only a priest (who is a good friend), family, and about ten friends. It was one of the most beautiful weddings I have ever been to.
I would worry about the Biblical principles of marriage (which the church continues to teach), not about the secular trappings of a wedding. I will base all my points on the theology described by St Paul in Eph 5 and other places about Christ's relationship to the Church. Marriage is a sign of Christ's love for His Church. (Eph 5), and the Church (that's you and me) is Christ's bride (Rev 19).
First, we know from our experience as Christians that Christ does not force us to be with Him. We each have a choice about being Christian and loving God. So, in marriage you should have that choice too. Both you and your future husband should
consent to the marriage.
Second, we know that eternity is forever. We are not going to get to heaven and then give up on God (nor will God give up on us). So, marriage is a
lifelong commitment. Otherwise we are not mirroring Christ's love for His Church. See John 4:17-18 and Matt 19:9 for examples of Christ's teaching on the 'for life' side of marriage. If a couple do not intend to stay together for life then I would say that is not a valid marriage.
Third, Christ has one bride, the Church. Christ does not have several people, He has one people. Us. God descibes himself as a jealous God, and idolatory (which is like being adulterous in your relationship with God) is against the first commandment. God expects us the be 'monogomous' in our relationship to Him, and so marriage should be
monogomous. It should be between one man and one woman only.
Fourth, The first thing God said to Adam and Eve after their marriage was to be fruitful and multiply, fill the earth. (I
do not want to get into a birth control fight. You are free to disagree with me, let's just not go there). God is
fruitful in our lives, and he gives us new life through our relationship with Him. So I think that if a couple do not intend ever to have children then the marriage would not be valid.
Finally, there are a couple of other things from the Bible which had an impact on how my husband and I planned our wedding. I do not believe these to be essential to marriage though. In Revelation the Church is described as dressed in white linen, the deeds of the saints. I wore white on my wedding day to emphasise the symbolism of the Bible, (well, that was
one of my reasons). Also, marriage is often linked with a feast (Cana, the wedding feast of the Lamb). For this reason it was important to us to have a meal with our guests after our ceremony.
Sorry about my super long post!