Sorry your mother lost her home to a tornado. Glad she got some help with building another.
The problem though is twofold.
1. Those Mennonites needed a belief in God to prod them into doing good works. That demonstrates a lack of internal drive of their own to do good works. In other words their good deeds don't come from the heart. from within. They were in a sense brainwashed to do good.
Now this should not be surprising as people are usually selfish by nature. Maybe that's from years of evolution where the selfish survived longer. Enough to procreate and carry on their genes.
It's a bit sad though that to do good deeds like that people have to believe fictional tales of a deity.
2. It's still dangerous because as easily as they were convinced to do good for the sake of a deity, they could be convinced by some malevolent leader to do bad. I know they weren't, but they could have been, and they still could be at some point in the future.
Ideally I'd like to see people help one another without having to be lied to. I'm sure that happens all the time even if it doesn't make headlines.
While that's a decent point (trying to explain to some people that you don't need a fear of punishment by a deity to not do bad things is like you're speaking a different language), evolution actually has done the opposite, and its likely the key that has made man the dominant species of the planet. Social interaction is what helped us survive quite a lot of things, and it's what enabled us to develop in ways that few species have. It actually generally takes the lies to make people war and destroy each other. Things are obviously more complex than that (as we've seen our social aspects be one of our biggest dangers due to disease or population issues, both of which that we've been able to thus far counteract via our intelligence).
You appear to be unfamiliar with the practices of communism under Lenin, Stalin, and Mao, which were hardly different from fundamentalist religion but killed tens of millions.
Weird that you're able to notice how they operated similar to fundamentalist religion without realizing that's what they effectively were. They pushed worshiping the State versus worshiping deities (although they often effectively pushed leaders or political parties as deities). It wasn't them pushing atheism, it was them stomping out all religion and beliefs that were counter to what they were pushing (purging). Outwardly (namely the Cold War, which was not really about Democracy vs Communism) them pushing Communism wasn't about them trying to tear down religions, it was about them pushing for relevance and control and was actually much more nationalism than anything (with regards to outward actions during that time, the US and USSR acted quite similarly really).