'AK-47 regret'

This article is very short, so first, please listen to the news article: Click here to listen

Questions:
1) Explain in your own words what Kalashnikov's regret was.
2) How did the church alleviate his concerns?
3) Do you know of other cases in which an inventor or researcher regretted his/her work?

If you couldn't catch everything from listening, then please see the article here.
You can see the full BBC article here.

Example answers:
1) He regretted that the product he designed had been used to kill so many people.
2) They said that the church supports those who killed people to protect the country, and also those who made the weapons to help them.
3) Einstein spent the rest of his life after World War II campaigning for the cease of nuclear weapons. Also, Nobel regretted people remembering him for his invention of dynamite, even though it could be used for peaceful purposes, unlike Kalashnikov and Einstein's work.