Originally Posted by TexasDreamer

Unfortunately, it will NOT be enough to just sent an affidavit (which is essentially what your letter is).
If you only send that, you will get denied for "Insufficient evidence to demonstrate continuous residence".
For an RFE any evidence is good evidence.
I've mentioned this before, dated pictures, print outs of facebook posts and check ins that show date and Nearby locations, tweets with dates, ebay account receipts, xbox live, anything that can tie you into the US is good....If a letter is the only thing youve got, get MORE than one! Neighbors, gym buddies, fellow church goers, etc....give them more than enough info, enough to show that you were here in 2011 without reasonable doubt...

Also, if you are actively involved in your church, im sure you do activities with other churches and other community orgs...get letters from their leaders as well...stating what yall worked on together, dates dates dates, and locations are key!

Hope this helps and best of luck!