When someone asked why Kerala is so different from a social harmony perspective, it got me digging deeper.

4 hours and another Kindle download later...... Quoting from Ivory Throne-

"In 1607, after a century of (Kerala) battling the Portuguese, the traveler Pyrard de Laval was still able to write:

There is no place in all India where contentment is more universal than at Calicut, both on account of the fertility and beauty of the country and of the intercourse with the men of all religions who live there in free exercise of their own religion.

It is the busiest and most full of all traffic and commerce in the whole of India; it has merchants from all parts of the world, and of all nations and religions, by reason of the liberty and security accorded to them there".

Though times have changed, a 2000 year tradition of cohabitation, starting with Christians (as early as 58 AD) could be one good reason.

Source- Pillai, Manu S.. Ivory Throne: Chronicles of the House of Travancore (pp. 13-14). HarperCollins Publishers India. Kindle Edition.