Thailand Religion FAQ
Ninety-five-percent of Thais are Buddhist. They practice the Theravada or "old school" of Buddhism. There are temples and monks nearly everywhere you go .. see Therveda Buddhism - Thailand
Thai religion is also heavily influenced by Hinduism. You will frequently see statues of Hindu gods and goddesses.
Finally, there are many elements of animism. The most visible signs of animistic influences are the numerous "spirit houses" near many businesses and some homes.
These small (actually some are pretty big) houses atop pedestals are given offerings of food, drink and flowers to show respect and gratitude to the spirits of the land.
Tourists are welcome at temples (called wats). Many monks like to practice their English. You should dress respectfully, take off your shoes before entering a temple and behave respectfully toward Buddha images (e.g., do not climb or sit on them).
Of the remaining 5% of Thais, most practice Islam. Provinces in the far South of the country are primarily Muslim.
Christians, Hindus and Sikhs make up a tiny percentage of the population.
For the most part, Christian religious services are only found in urban areas, although there is the occasional one in rural Thailand.
As far as churches go, Catholic and Baptist seem to be the most common.