Your argument would be plausible if what one experiences after death were the -sole- line of evidence for theism.
My argument would be plausible? Dude, I'm saying that you can't use observation X as evidence to support your explanation of observation X. If I a scientist said, "The reagents react together to produce a jelly. I hypothesize that angels are creating the jelly. The jelly is produced, therefore the angels hypothesis is supported," We'd all say he was nuts. And I wasn't arguing that it was the *sole* argument for theism. I was addressing just that one because it's a particularly bad argument.
Fulfilled prophetic claims are another.
How does one keep score on fulfilled prophetic claims? Like, how does, say, the Bible stack up against Nostradamus or the Koran?
Willing martyrdom of contemporaries is another.
The fact that people believe in something hard enough to die for it also isn't really very strong evidence that it's true. Are we saying that Islam is getting more plausible by the day?
I will say this--if a religion says that you experience X when you die and X looks nothing like the near death experiences people report, that's good evidence that the religion in question is not true. But failing to reject a hypothesis when the hypothesis was written to explain the observation is not exactly a big win. As they say, you can kill sheep with witchcraft if you also feed them arsenic.