If you do send a letter, here are a few options you might consider:
1. Include a bill for reimbursal of all the contributions you made while in. Itemize carefully and indicate it should be paid in full in 30 days or else...
2. Tell them Jesus told you to do it. Be as authentic as possible.
3. Write it in crayon and draw some pictures - stick figures of you.
4. Make a fold out and use Michael Jacksons face.
5. Put a picture of a really cool sports car and say this is another reason you left.
6. Ask if everyone you knew was able to get over the STD's they contracted on the last Intl' Convention - be sincere.
7. Ask if they could drop by the local Catholic parish where some kind fellows were asking for a visit. Give the address. Make it believable.
8. Do nothing and live your life, find joy, have a great meal and an even better beer.