I have a concept for you to contemplate. Now, you will have to keep in mind that this is an unorthodox concept as far as this board is concerned and I'm sure to draw fire for it, but here goes.
What is it that the Bible says about marriage? The Bible says that marriage is God ordained.
So God created man in his own image, in the image of God he created him; male and female he created them. Genesis 1:27
For this reason a man will leave his father and mother and be united to his wife, and they will become one flesh. Genesis 2:24
The Bible defines the role of the husband and wife in the union. This can be found in Ephesians 5:22-33.
However, and this is what's going to get me into trouble with the radicals and fundamentalists, NOWHERE in the Bible is a ceremony mandated. To take this one step further, NOWHERE in the Bible is a certificate of marriage mandated. Rather the man will leave his father and mother and be united to his wife. The only certificate mentioned in the Bible that I know of, as it pertains to marriage, is a certificate of divorce permitted by Moses.
A marriage ceremony is simply a matter of tradition, then, and preference.
What about a marriage certificate? It's a nifty little way for the government to conveniently cash in on a concept and give them some semblance of control. Don't forget, according to Canadian laws you are considered a common law union after living together for one year. Three years entitles you to much the same protections and rights as a legally wed couple.
However, in the United States it's a little different. Only fourteen states recognize common law marriages. In order to be entitled to certain legal rights, such as child custody rights, spousal support, entitlement to government benefit programs, etc, you must be legally wed.
Considering the aforementioned, I would challenge that the only consideration you need to make when considering a marriage certificate is whether you want to be assured of every right and benefit available to a legal union.