Weddings are challenging--both to the photographer's skill level and to his or her equipment. Church's and receptions halls are often dark. The action can be fast. And the imges are once-in-a-lifetime. This is not the time to compromise. My high end equipment and many years of experience are your assurance.
At weddings, I have three Canon 1 series cameras. These are regarded as "top of the line" and have many advantages over their lesser bretheren. They have great low light capabilities, produce magnificent color, and record simultaneously to two memory cards. While a memory card is unlikely to fail, it can happen and this is one risk you want to avoid.
I also use high-end "L" lenses and, as much as possible, prime lenses. The lenses I use are:
200 2.0 L. This is probably the best ceremony lens currently available. Because of its high cost (almost $6000) very few wedding photographers use this.
135 2.0 L. This is a great reception as well as ceremony lens.
100 2.8 L macro. This is a new version of a highly regarded lens. The macro function is great for ring shots.
85 1.2 L. This is regarded as one of the finest portrait lenses available. It is much superior to its lesser 85 1.8 sibling. This is the new version of this lens.
50 1.2 L This is an excellent low light lens for "normal" perspectives.
35 1.4 L. This is a wide angle lens. I'll use it for formals as well as for some wide angle reception shots.
14 2.8L. This is a super wide angle lens that is great for photographing the entire church at once or wide dance floor shots. This is the new version of this lens.
There are times, when you're not quite sure what's going to happen next, when zoom lenses are necessary.
70-200 2.8 L. This is regarded as one of the finest zoom lenses made. Many photographers use it for the bulk of their wedding shots, but while very good, it is still not equal to the equivalent prime lenses.
24-70 2.8 L. This is a widely used zoom.
I use Profoto studio lights for both the formals and as background lights at the reception. These are battery powered which can be really useful in many churches and allows better placement at the reception. I also use Quantum flashes.