Christians what should the punishment be for people believing in other religions? ?

None in this World.

God will (rightly) assign any merited punishment in the next.

Exception: religions that practice (religiously) such illegal things as human sacrifice, child molestation, etc.

Punishment is not the exact word. It is more like consequences of your free-will decision to reject God. The consequences are predictable and public information.

I don't know what barbarian country you live in, but I live in the US -- where people are free to believe, or not, as they choose.

it is not up to anyone to punish a person for believing in another religion

Oh now now, my darlings. God and Jesus make it vastly clear that if you're worshiping other gods or even not worshiping any gods at all, you are toast. You are the enemy. You are to be converted or...yeah. All this feel-good, whatever you do is great with God, even if another religion blah dee blah...nope. Now, if you have secular laws saying all religions or lack thereof are welcome here...I guess that means your God's ultimatums got supplanted by commies or something.

Hope this helps!

Thou shalt have no other gods before Me. Love God, love thy neighbor as thyself. Same sentiment, dolls.

The punishment should be to follow it.

I live in the United States where people are free to worship as they see fit. It is stated in the 1st Amendment to our Constitution.

WITHOUT JESUS NOBODY PASSES JUDGMENT.....THOSE WHO REMAIN UNsaved will fail and go to fire..

But then which Christian religion, there are more than one.

Is Baptist the only right one, or maybe Pentecostal is the only right one. If believing in another religion is punishable by death, then a lot of Christians would die too.

People aren't going to punished when they have a different faith or lack of belief in God.

We will leave this up to God.