I (Google/ Alexa) just did a very interesting calculation.
If there are c.350,000 Messianic believers in the world, out of c.8.1 billion, they are an incredibly tiny minority: 0.004%
I’m not sure whether or not this figure makes any distinction between Jewish or gentile-born Messianics, but I suspect that we can assume not. In other words, I think this figure includes both.

I won’t make any additional comments on this right now (I shall ponder for a while), other than to compare the Christian population, which is 2.28 billion or 33%, and the mainstream Jewish population, which is 14.8 million, or 0.2%.
Figures from 2020.


