Many years ago I worked on a project in Amritsar, which had me regularly engaged with the Golden Temple (the most sacred place in the Sikh religion) authorities. I have to say that all the Sikhs I interacted with were fantastic: honest, generous, hard-working, fun-loving, good-hearted people. I do think a lot of this was grounded in Sikh religious principles, which promote a kind of radical moderation that's actually pretty unique among religions. (the story goes that the founding guru of the Sikhs had two sons, one of whom destroyed his life with gambling and alcohol, and the other of whom destroyed his life with asceticism and abstinence. The guru repudiated both of them, saying that the latter was as much of a vice as the former. Instead, he preached that the point of life was to be happy, and to make other people happy: have a family and take good care of it, take care of other people, don't be an asshole, and have a good time. Balance these imperatives well, and you're doing God's work. As far as organised religions go, it's really pretty great.
And langar at the Golden Temple is a truly amazing experience. Men and women from every strata of society, from every religion, sitting down together to eat good food in silence. No preaching or any other bullshit -- the shared togetherness and humanity is enough. Honestly, it's profound. One of my dreams for later in life, when I have the time, is to go back there for a few weeks and volunteer to cook in their kitchen.
That said: Sikhs aren't all cuddles and sunshine. Early in their history they were strictly pacifistic, and also heavily persecuted. After a while, one of the head Gurus decided that if the way to do God's work was to live a good life, and there were oppressors who were committed to preventing you from doing so, then a necessary part of God's work would require, er, helping those oppressors to reincarnate as quickly as possible. Ever since then, they haven't been keen on turning the other cheek, and have had a very strong martial/military culture. There's still a very strong ethic that you shouldn't use violence unless there's absolutely no alternative -- but if you do have to use violence, then you might as well be bloody good at it. But of course the more that one participates in violence, the greyer the morality becomes. So I wouldn't dare wade into the India vs. Khalistan conflict: I'm sure that many of the beefs on both sides are well-founded at this point. But if you can separate the culture and the religion from the politics -- then yeah, it's a really great thing they've got going on there, and I think it's great for the world to have more exposure to it.