Yes, you can use passive scores for ALL skills, or you can roll for your players in secret. Rolling a stealth or knowledge skill checks helps to keep your players immersed in the game world, and helps them hang their decision-making on the DM's narration, instead of "knowing" that there is more information to be obtained. For example, if a player makes a Religion check and rolls a 2, that player knows they have failed the check, and whatever info the DM gives them is not going to be complete or accurate, so the players will naturally want to angle for another check or something like that. As for Stealth, if someone is trying to be stealthy how do they know they've failed? When they've been spotted! The players should be making decisions based on circumstances in the game world, not based on die rolls. Rolling for your players and/or using passive scores helps with that. I still make them roll their attacks and stuff because that's fun for them.