An apparently extraordinary command

Surely we're to pray about anything & everything, anyone & everyone, arent' we? 
Well, no. In Jeremiah 7:16, God tells Jeremiah, 

As for you, do not pray for this people, or lift up a cry or prayer for them, and do not intercede with me, for I will not hear you.

And then in 11:14

Do not pray for this people, or lift up a cry or prayer in their behalf, for I will not listen when they call to me in the time of their trouble.

Why not pray for them? The answer given is that they have broken the covenant and are persisting in their worship of idols. They have made their own gods of wood and stone, and think that prayers and sacrifices to these idols will save them from disaster. Meanwhile, when Jeremiah speaks the word of the LORD, they threaten to kill him (11:18-23).  


But what of the NT? Well, there's an echo of this in 1 John 5

If anyone sees his brother committing a sin not leading to death, he shall ask, and God will give him life—to those who commit sins that do not lead to death. There is sin that leads to death; I do not say that one should pray for that. All wrongdoing is sin, but there is sin that does not lead to death.

Of course here there's the added complication of the 'sin that leads to death' and 'the sin not leading to death.' But in the context of 1 John andtaking into account the OT background, it seems as if the unforgivable sin is turning away from the covenant God makes with his people. That's certainly the context in Jeremiah, and in 1 John, the 'liar' and the 'antichrist' is anyone who knows the truth that Jesus is the Christ but denies it. (2:18-23 & 4:1-6). To deny Jesus as the Christ is to deny the Father and to forfeit life. 

But does this mean that we're not to pray for non-Christians to come to faith? No. This is a specific command about those who know the truth and have abandoned the truth. In the OT, it was God's own people Israel. In the NT it's those who 'went out from us' because 'they were not of us; for if they had been of us, they would have continued with us. But they went out, that it might be plain that they are not of us.' (1 John 2:19). Once people have heard about Jesus and know full well who he is and not only reject him but teach against him (4:1) then it would seem that there's no point in praying for them. That sounds incredibly harsh because it is, and because it's so harsh it means we should not quickly asign anyone to this category. We don't have that clear command not to pray that Jeremiah had, so it's surely better to pray and have the prayer unanswered than to assume we know where people stand in relation to 'the sin that leads to death.'