Nicholas Thalasinos, 52, identified as a Messianic Jew and passionately defended Israel, actively debating about religion in online forums and in person, his friends said.
Only two weeks ago, Thalasinos, of Colton, was having a heated on-the-job discussion about the nature of Islam with Syed Rizwan Farook, his fellow restaurant inspector and one of the shooters.
Thalasinos' friend, Kuuleme Stephens, told The Associated Press that she happened to call him while he was working with Farook and that he brought her into their debate, loudly declaring that Farook "doesn't agree that Islam is not a peaceful religion."
She heard Farook counter that Americans don't understand Islam, and Thalasinos responded by saying, "I don't know how to talk with him," she said.
Thalasinos' wife, Jennifer, told the AP the two "probably did have debates" but "I never got the impression it was in a bad way."
"It was more, you know, just having discussions about religion and faith," she said.
She said she believes her husband died a martyr because of his faith but he never indicated that Syed had radicalized. She said she did not believe her husband was individually targeted.
"They all got along really well. So it's shocking," she said.