"The pain in my soul is unbearable," Mikhail Kalashnikov said in an emotional letter April 7, some eight months before he died, to the leader of the Russian Orthodox Church.
"I keep asking myself the same unknowable question: If my rifle deprived people of life, does it mean that I, Mikhail Kalashnikov, age 93, the son of a peasant and an Orthodox Christian, am responsible for people's deaths, even if they are enemies?" he said in the two-page, typewritten letter to Moscow Patriarch and Russian Orthodox Church Primate Kirill, published in pro-Kremlin newspaper Izvestia.
"The longer I live, the more this question drills itself into my brain and the more I wonder why the Lord allowed man to have the devilish desires of envy, greed and aggression," Kalashnikov said.
He hand-signed the letter, "A slave of God, the designer Mikhail Kalashnikov."
Kalashnikov, who was baptized at age 91, died Dec. 23 at age 94 in Izhevsk, the capital of the Russian republic of Udmurtia, where he lived.
Russian President Vladimir Putin attended his funeral.
The AK-47, which Kalashnikov developed in 1945, remains in its later variants the world's most popular firearm because of its durability, low production cost, availability and ease of use.
More than 100 million of the assault rifles are widely believed in use around the world.
For years, Kalashnikov, a retired lieutenant general, refused to accept responsibility for the many people killed by his weapon, saying it was designed to protect his homeland, not to be used by terrorists or thugs.
"This is a weapon of defense," he said. "It is not a weapon for offense."
But in 2008 he admitted, "It is painful for me to see when criminal elements of all kinds fire my weapon."
Kalashnikov's daughter, Elena, told Izvestia she believed a local priest helped her father write the letter.
A church spokesman was quoted in the newspaper as saying Kirill received the letter and wrote back.
"The Church has a very definite position: When weapons serve to protect the Fatherland, the Church supports both its creators and the soldiers who use it," Press Secretary Cyril Alexander Volkov said.
"He designed this rifle to defend his country, not so terrorists could use it in Saudi Arabia," Volkov said.
Kalashnikov received many Soviet honors, including the Order of Lenin, the Soviet Union's highest decoration, but made little money from his gun.