Why do some societies abandon/change their religion?

[Puffin]

I was having a discussion on another forum, and this question came up. When you look at major religions today, it seems incredible that 1500 years ago, it was reportedly possible for St Patrick to convert Ireland from their traditional beliefs to Christianity. How did he do it? Christian missionaries have had similar successes with, say New Guineans in more recent times, reportedly telling them to burn their "pagan artifacts" and being obeyed. The Christianization of Iceland seems even more bizarre, seeing as it was done largely democratically, and with the decision that the country should become Christian being made by a Pagan priest called Þorgeirr Ljósvetningagoði.

My best guess was that most societies that switch religions are converted by a combination of awe at the missionaries' technology/fine clothes/weapons, and that many of the old religions had never previously had to compete with other religions by means of theological debate, at which missionaries were well practised. It may also help if the society has had a recent spate of severe hardships.

Can anyone provide a better, or at least better researched, answer?

 

[ray b]

some religions were invented to be easy to convert to
thank paul/saul for that as he revised jewish beliefs
but droped the hard or painful parts to make it simpler
mohammad did much the same
so they have the two bigger religions now

I don't think a aztec like religion would be very easy to gain converts short of war

 

[arildno]

I was having a discussion on another forum, and this question came up. When you look at major religions today, it seems incredible that 1500 years ago, it was reportedly possible for St Patrick to convert Ireland from their traditional beliefs to Christianity. How did he do it?

The Christianization of Iceland seems even more bizarre, seeing as it was done largely democratically, and with the decision that the country should become Christian being made by a Pagan priest called Þorgeirr Ljósvetningagoði.
Can anyone provide a better, or at least better researched, answer?

Both of these are reformations "from the top".

St. Patrick were able to gain converts among the chieftain class, and they, either out of genuine faith, or that Christianity as a "tool" was convenient for them to institute, made it their "official" religion. Similarly on Iceland.

Once a "critical mass" of chieftains PROFESSED Christianity, it would be inadvisable for other chieftains not to do so, i.e, a snow-balling effect of pretense followed, where the earlier pretence become substituted with genuine faith in later generations.

A similar picture holds with 7th-8th century Arabia, when most likely personally pagan Arab chieftains made a public conversion to Islam in order to keep, or augment, their position of power.

Christian missionaries have had similar successes with, say New Guineans in more recent times, reportedly telling them to burn their "pagan artifacts" and being obeyed.

This one is rather different.
Here, I strongly suspect that systematic taboo-breaking WITHOUT ILL EFFECTS brought about a disenchantment among the populace, i.e, they saw that their former religion had to be untrue, since the much-feared repercussions did not come about.

Or, a combination of the two is a valid picture some places:

Earlier polytheists were well familiar with that different gods had different powers.
One prayed to that God, or those gods who were most powerful, or most likely to intervene in a particular situation.

When a new God comes along and beats the heck out of the old ones (i.e, taboo-breaking does not lead to disaster), the rational reaction is to join up with that God, not necessarily accepting or understanding that this switch formally is a break between earlier polytheism and new monotheism.
For the polytheist might remain a polytheist at heart, but having seen enough evidence that the new monotheist god surely is at least the most powerful one.