In no particular order...
According to census data from around the world, more people claim to follow the "Jedi" religion than the Christadelphian one. In 2011, the number of people in Australia alone who put "Jedi" as their religion was higher than the total number of Christadelphians in the world.
Scientology grew faster than the Christadelphian religion.
There are many more Jains, Rastafarians and Zoroastrians (each, not combined), than there are Christadelphians.
The average person is more likely to be struck by lightning during their lifetime than become a Christadelphian. This includes being born into the religion.
More people get struck by lightning each year than the number of non-Christadelphians who join the religion over the same period.
There are more elephants than Christadelphians.
There are more whales than Christadelphians.
Here is a chart of world religions. Christadelphians are not listed on it.
And finally...
The ratio of Ex-Christadelphians to Christadelphians is greater than the ratio of Christadelphians to the rest of the world.
This would still be true even if there was only one Ex-Christadelphian.
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Now of course, this is all just a bit of fun and obviously doesn't mean anything. Truth isn't determined by the number of people who believe a thing, and so on.
But suppose the Christadelphians are right. This leads to some bizarre outcomes such as two billion Christians somehow failing to interpret God's apparently clear message to them, and then being judged for it even though an all-knowing God would've known the text wouldn't be understood when he authored it. Millions of people in other religions somehow thought other texts were written by God instead. But perhaps most striking of all is the realisation that your family of birth becomes the single most influential factor on whether or not you would be saved.
For the Christadelphian readers, you must feel incredibly lucky to have been born into the "one true religion", especially after realising how statistically unlikely it is that you would have become a Christadelphian otherwise.
To put it another way, you were more likely to be born into a family in the top 1% financial bracket than to be born into a Christadelphian family. I apologise if that causes you to feel some regret.
For the rest of you who are not Christadelphians and wondering why you're so apparently unlucky, it's just statistics. There are just many things that are statistically more likely than you being or becoming a Christadelphian.
Probably you were born into a non-Christadelphian family. Maybe you haven't yet been struck by lightning.
Or maybe you're an elephant.