Qur’an 9:29—Fight those who believe not in Allah nor the Last Day, nor hold that forbidden which hath been forbidden by Allah and His Messenger, nor acknowledge the Religion of Truth, from among the People of the Book, until they pay the Jizyah with willing submission, and feel themselves subdued.
Qur’an 9:73—O Prophet! strive hard against the unbelievers and the hypocrites and be unyielding to them; and their abode is hell, and evil is the destination.
Qur’an 9:123—O you who believe! fight those of the unbelievers who are near to you and let them find in you hardness; and know that Allah is with those who guard (against evil).
We know from Western politicians and the media that no Muslim takes these verses seriously. So Pechyonkin must have turned to violence for some other reason. I guess we'll never know why.
The suspect, identified as Pavel Pechyonkin, worked as a paramedic with an ambulance service but left home in 2011 and joined Dagestani militants after converting to Islam and changing his name to Ansar Ar-rusi.
In response to his parents' video appeals for him to come home, Pechyonkin posted his own video online this spring, saying he was following God's will and would not turn back.
"I have come here only to make Allah pleased with me, to earn heaven," he said in the video.
In a plea by his parents recorded in March, his father, Nikolai, admonished his son to "drop those weapons" before he would become a "terrorist."
"Do all Muslims go around with weapons?" the father said in the video. "You are the only one so stubborn. What harm have people done you? […] You are going to kill children."
His mother, Fanaziya, said that she was also a Muslim, and pleaded with her son that he should abstain from using violence.
"What kind of the Koran…" she said, apparently too pained to finish the sentence, before finding the strength to continue: "I don't believe that Allah has ever said that one must kill people." (Continue Reading.)
Pechyonkin's mother doesn't believe that Allah has commanded Muslims to kill. Apparently, she hasn't read the Qur'an, which defines Muslims as those who "slay and are slain":
Qur’an 9:111—Surely Allah has bought of the believers their persons and their property for this, that they shall have the garden; they fight in Allah's way, so they slay and are slain.