As long as nobody is harmed you can do (and therefore also believe) whatever you want.
It's simple human rights (that derived from various religions so no bashing needed from either side) and, of course, they do have limits, e.g. there's not only "freedom" but also "equality" so you shall not limit anyone's freedom by doing whatever you want.
People say things like the Golden Rule would be enough
https://en.wikipedia.org/wiki/Golden_Rule
but I don't think so. People who kill (doesn't matter if for religious reasons or not) probably wouldn't mind getting killed themselves so the Golden Rule doesn't apply.
So, line 1, beliefs should be tolerated as long as nobody is harmed. Just like kids' behaviour should only be tolerated if nobody (incl. themselves) is harmed but the world seems to tend to tolerate anything and everything now unless it is against their own lifestyle/belief.
Issue with this is: what is "harm"? Is only hurting people harming them or also getting on their nerves or penetrating their intimate zone, smoking around non-smokers/kids, producing goods in a dirty way? Pretty deep topic.