Part of the purpose of the great commission is to warn even those people who choose not to believe. This is an ultimate "don't say I didn't warn you" type of situation. Here's some scripture references dealing with this.
For the grace of God that bringeth salvation hath appeared to all men,
<Titus 2:11
Again the word of the LORD came unto me, saying,
Son of man, speak to the children of thy people, and say unto them, When I bring the sword upon a land, if the people of the land take a man of their coasts, and set him for their watchman:
If when he seeth the sword come upon the land, he blow the trumpet, and warn the people;
Then whosoever heareth the sound of the trumpet, and taketh not warning; if the sword come, and take him away, his blood shall be upon his own head.
He heard the sound of the trumpet, and took not warning; his blood shall be upon him. But he that taketh warning shall deliver his soul.
But if the watchman see the sword come, and blow not the trumpet, and the people be not warned; if the sword come, and take any person from among them, he is taken away in his iniquity; but his blood will I require at the watchman's hand.
<Ezekiel 33:1-6
Remember the word that I said unto you, The servant is not greater than his lord. If they have persecuted me, they will also persecute you; if they have kept my saying, they will keep yours also.
But all these things will they do unto you for my name's sake, because they know not him that sent me.
If I had not come and spoken unto them, they had not had sin: but now they have no cloke for their sin. He that hateth me hateth my Father also. If I had not done among them the works which none other man did, they had not had sin: but now have they both seen and hated both me and my Father.
But this cometh to pass, that the word might be fulfilled that is written in their law, They hated me without a cause.
<John 15:20-25
For every one that doeth evil hateth the light, neither cometh to the light, lest his deeds should be reproved.
But he that doeth truth cometh to the light, that his deeds may be made manifest, that they are wrought in God.
<John 3:20-21
But take heed to yourselves: for they shall deliver you up to councils; and in the synagogues ye shall be beaten: and ye shall be brought before rulers and kings for my sake, for a testimony against them.
And the gospel must first be published among all nations.
<Mark 13:9-10
And he said unto me, Thou must prophesy again before many peoples, and nations, and tongues, and kings.
<Rev. 10:11