However I also know many people who pray the DMC each day for those who have died in a state of mortal sin
no use. if your very sure he or she is leading a sinful life,it all depends upon the mercy of the Lord we never know fully
should we pray for those who die in a state of mortal sin or is there no use praying for them?
there is no use for praying for them.as in Luke 16: 22 The poor man died and was carried away by the angels to be with Abraham. The rich man also died and was buried. 23 In Hades, where he was being tormented, he looked up and saw Abraham far away with Lazarus by his side. 24 He called out, ‘Father Abraham, have mercy on me, and send Lazarus to dip the tip of his finger in water and cool my tongue; for I am in agony in these flames.’ 25 But Abraham said, ‘Child, remember that during your lifetime you received your good things, and Lazarus in like manner evil things; but now he is comforted here, and you are in agony. 26 Besides all this, between you and us a great chasm has been fixed, so that those who might want to pass from here to you cannot do so, and no one can cross from there to us.’ 27 He said, ‘Then, father, I beg you to send him to my father’s house— 28 for I have five brothers—that he may warn them, so that they will not also come into this place of torment.’
29 Abraham replied, ‘They have Moses and the prophets; they should listen to them.’ 30 He said, ‘No, father Abraham; but if someone goes to them from the dead, they will repent.’ 31 He said to him, ‘If they do not listen to Moses and the prophets, neither will they be convinced even if someone rises from the dead.
Jeremiah 11:14 As for you, do not pray for this people, or lift up a cry or prayer on their behalf, for I will not listen when they call to me in the time of their trouble. 15 What right has my beloved in my house, when she has done vile deeds? Can vows and sacrificial flesh avert your doom? Can you then exult? 16 The Lord once called you, “A green olive tree, fair with goodly fruit”; but with the roar of a great tempest he will set fire to it, and its branches will be consumed. 17 The Lord of hosts, who planted you, has pronounced evil against you, because of the evil that the house of Israel and the house of Judah have done, provoking me to anger by making offerings to Baal.
1 John 5:16 If you see your brother or sister committing what is not a mortal sin, you will ask, and God will give life to such a one—to those whose sin is not mortal.
There is sin that is mortal; I do not say that you should pray about that. 17 All wrongdoing is sin, but there is sin that is not mortal.