Unless you have a good ad blocker, or Mormon.org has an "Opt Out" button (Which is doubtful), there is not much you can do. If you use Google Chrome as your browser, Google adapts their ads to your browsing habits. So naturally if you search mormon or ex-mormon quite a bit, most of your ads are going to be mormon related.
The LDS church is spending tons of money on advertising on the web. Google is goofing up and sending the ads to someone like you, who it isn't going to work on. Congratulations! You just wasted some of the churches billions!
The best thing to do is to click on the ads. This will cost the church some money and you will have done your part to make the world a better place by depriving the church of funds that would otherwise sucker some gullible soul. Also, you are directly some of the funds from the church to Google, Inc. which is more likely to use the money in some charitable cause.