I’ve always thought so especially if they are a tinok shenishba. Even if someone is not a tinok shenishba, I would still think that he could be a tzaddik especially if he is someone who saved someone’s life, whether physically or emotionally.
I’ve also always been under the impression that someone who dies “al kiddush Hashem” (religious or not) is considered to be on an extremely high level. (I think there is something specific said about such a person – I forget what, but I know they are considered to be on a really high level).
And anyone who is killed because he is Jewish is considered to have died “al kiddush Hashem”.
btw, there is a really fascinating book called “Gutta: Memories of a Vanished World” by Gutta Sternbuch & David Kranzler about her experiences as a Bais Yaakov student and teacher before and during the War.
At one point, she worked in Korzak’s orphanage. He used to encourage her to teach the kids about Yiddishkeit and Emunah. He told her that it’s too late for him, but he thinks it’s good for the kids to learn about Emunah and Yiddishkeit.
I am not Hashem and I don’t know His Judgments, but based on what I know of Korzak, I would imagine that I would have what to be jealous of in terms of his Cheilik in Olam Haba. (Although at the same time, he has what to be jealous of my cheilik in Olam Hazeh).
We don’t know Hashem’s Judgments, and we don’t know each person’s story – his Mitzvos and his aveiros and his life-story and the specific challenges he had to overcome. Hashem judges each individual based on his potential and how well he fulfilled it.
There are so many factors that go into judging a person and most of these factors are unknown to others. That is why we can never (or almost never if not never) judge another person.