Where's the best place?
I may start typing one here as an answer, then move it to a better place when I get a better answer. Thanks,
In stark contrast to almost all other structures across the SE network, elections are the one time when voting is done on the basis of the person not a particular piece of content.
The character limit is a fairly new thing across SE elections. As I understand it the purpose is to limit the tendency for elections to become a contest between platforms and ideologies. In difference to some political elections that are largely issue based and the character of the candidates is considered by some to be less important than the platform they are running on, SE moderators are not necessarily empowered to create or dictate policy. As a moderator whether you agree or disagree with community consensus your job will be to enable by enforcing whatever the consensus is. Even if moderator with very different ideals got elected, their election would not be a license to run rough shod over everybody else in another direction.
By keeping the copy part of nominations short, voters are more likely to vote on a balance of factors rather than on the content of a campaign statement. For starters, they might actually read through them all the options and consider them in a balanced manner (as opposed to writing off candidates whose posts are too long to read or too short to show what they stand for if they are an unknown or whatever other factors there may be). They are also more likely to vote based on other factors like their knowledge of the candidates previous meta participation, chat interactions, history of site actions, etc.
If your previous meta history and other site interactions doesn't already make your position and character clear, this is something to think about in the future not the week of but even years before elections. Even if you aren't selected this time, keep this in mind because there will be future elections on Christianity.SE too.
You can of course make as much information about yourself and your ideas as you like available through another venue. The SE team has suggested replying to the election announcement post with extended nomination data as answers if you'd like that option. You could also write something up off site and link it from your nomination. Also be sure to participate in chat and town-hall meta events that will be upcoming.
There really isn't a great way for you to post an epic mega statement. Moderator nominations used allow for much longer statements, but then CasperOne happened.
There are some other venues for making your statement if you'd like to take advantage of them. However most of them will be external from the moderator nomination so there is that.
You could make a Youtube video about yourself and you policies. A gaming.se mod did this once and it was pretty cool (though he didn't win election)
You could create an external document in google docs or similar and share it in your nomination.
You can participate in the officially sanctioned moderator Q&A that will go on when the election starts.
You can help organize a moderator town hall chat with as many candidates as we can get together.
You can make meta post for all of the candidates to post an extended platform as answers.
These are the ones that I can think of. However, I think the single most important things you can do are to be active and visible on the site, write a thorough, but succinct nomination and work on your stats (the ones shown in your profile and also the ones that are shown here (whenever we get added to that))