Rensselaer has a small Jehovah Witnesses hall on West Maple Street. According to the sign in the front, there is a public meeting at 9:30. The local hall does not have a website.
The Jehovah Witnesses are adventists, that is, they expect the imminent return of Jesus. The official website of the Jehovah Witnesses explains:
In themselves, recent world happenings are bad, but what they signify is good, namely, Christ's presence. The conditions mentioned above started to be evident in that widely heralded year 1914! It marked the end of the Gentile Times and the beginning of the transition period from human rule to the Thousand Year (Millennial) Reign of Christ.The Witnesses have a number of practices that have brought them into conflict with others, such as their refusal to accept blood transfusions:
Thousands of physicians around the world are now successfully treating patients without using blood transfusions. In a spirit of respect and cooperation, Jehovah's Witnesses desire to share some findings in regard to transfusion-alternative strategies.The official website has nothing on the history of the group, but you can find it on Wikipedia.