Unitarian Universalist churches are often very open and non-dogmatic. I've attended as an agnostic and a theist. I've also met atheists there.

I recommend Meetup.com. My area has some atheist/agnostic groups and if yours doesn’t, you could start one.

I gotta go with the 'meetups.com' groups. There are lots of them and it is a great way to get to know like minded people of all interests.

Indianapolishas a secular assembly. I am not sure if there are others any closer to you.

[indianapolis.sundayassembly.com]

The Unitarians, are nondenominational, and they welcome, free thinkers, atheists and agnostics. It is still kind of churchy though.

There is also the Sierra Club if you are an outdoor activity family.

You might be able to make contacts via the meetup.com groups, as they would know what is available locally for you.

Indiana is a tough state for an atheist or agnostic to live in.

check out the Unitarians; www.uua.org

Try meet up groups on line. If you do not find atheist/agnostic groups, you may find science oriented groups, or those interested in other activities which do not involve religion.