Yes, Estonians aren’t religious, but religious freedom is guaranteed by the republic as one of the constitutional rights.
The latest census counted 25 Christian denominations and 40 other faiths from all over the world present in Estonia. This includes both the ancient and well-known (e.g. Buddhism, Hinduism, Islam, Taoism, Judaism) and some more recent practises (e.g. Light Bearer, Brotherhood of Violet Flame).
No worries, you can still practise your faith in your accustomed manner in here, just don’t be surprised if your colleagues aren’t as passionate about matters of doctrine – about 60% of people don’t “profess any religion” in Estonia.
Technically, Estonia is predominantly a Christian country. Recently, Russian Orthodox has become the primary church of choice for many believers, succeeded closely by the traditional Lutheran one.
Other sizeable Christian confessions are: Baptist (4,507 people), Roman Catholic (4,501), Jehovah’s Witness (3,938), Christian Free Congregations (2,189) and Adventist (1,194).
Currently, many “roots” disciplines are going through a revival and neopaganism is gathering momentum.
Although the non-religious people of Estonia aren’t that pre-occupied with the higher power, they are still as curious about the Great Beyond as people are in other countries. Just check the esoteric sections in the bigger bookshops.
There’s also a great body of work gathered on the old Estonian traditions in a web archive Folklore.ee.
P.S. There is no such thing as an official Estonian folk religion – that was an artificial construct devised by scholars in the 1920s and 1930s.