My slightly snarky answer is to drop to my knees and yell “Don’t worry, I’m praying for you.” 'Cause that is what they both advocate, isn’t it?
But (stupid Samaritan parable) I’d probably try and do something physically useful.
I am afraid I’d jump in and help one of the fuckers. Likely Ann 1st. Damn.
Well, we can’t all be bad citizens.
Aw, FisherQueen and Merhouse beat me to it on the “tell them I’m gay” thing. I mean, I’m not even gay; I’d just love to see the looks on their faces. 
Seriously, though, if this happened in front of me, I would drop to my knees and thank the Lord, for this would finally give me irrefutable proof that there is a God. And then I would go to lunch.
Well, actually, I suppose I’d do what I could to help, but I’d feel unclean for months.
feign deafness.
failing that, feign inablility to swim.
failing that, feign inability to make snap judgements.
Smile sweetly, say “Karma is a bitch, isn’t it?” and turn and walk away.
Maybe three steps, and then call 911 / swim in / do the appropriate Right Thing to Do. Ahhhhh, I’m a sucker. 
Hit myself on the head with the anvil, just hard enough to be unavailable to help for a while. Nobody would find you morally bankrupt for a lack of action if you’re out cold.
Run.