Theists, why that religion?

[Justtristo]

If we had opened our eyes to the light under the shadows
of St. Peter's at Rome, we should have been devout Catholics; born in the
Jewish quarter of Aleppo, we should have contemned Christ as an
imposter; in Constantinople, we should have cried "Allah il Allah, God is
great and Mahomet is his prophet!" Birth, place, and education give us our
faith. Few believe in any religion because they have examined the
evidences of its authenticity, and made up a formal judgment, upon
weighing the testimony. Not one man in ten thousand knows anything
about the proofs of his faith. We believe what we are taught; and those are most fanatical who know least of the evidences on which their creed is
based.

--Brig. Gen Albert Pike, C.S.A.

My main criticism of that assumption is that people do change their religious views quite a fair bit. Otherwise we would have not seen sub-Saharan Africa turn from mostly pagan to Christian since the late 19th century, likewise with the increase in the number of Christians in Korea and China. Not to mention the number of ex believers in some religion or another on these forums.

Mind you the world has become more of a "market place" for religions than it has been in the centuries before.