There has to be reckoning for sin at some point, Muman. That is perfectly clear in Tanach.
Not being raised to believe in G-d is not an excuse for any human being. Creation (i.e. the earth and everything in it) itself is living testimony to the fact that there is one creator G-d who made everything. All of the basic laws (i.e. Noahide) of morality are programmed into the human heart as well. It is obvious that it is inherently wrong to murder, steal, lie, have homosexual/adulterous/fornicating relations, torture animals, etc. When people do these things anyway, it is a willful choice, not a matter of ignorance.
Bones,
You are harsh to judge, and that is a sign that you will be judged harshly... But Hashem is a merciful father who waits patiently for his children to return to him. I have found that when I judge others with mercy, I too am judged with mercy.
Hashem has told us that he will be with us when we return. It is not for you, or I, to say who is going to sit in heaven with the Master of the Universe. We can judge based on our understanding, and we can rebuke when we see evil, and we can stand up against injustice and cruelty. But the ultimate judge is Hashem. I have seen many cases of people going off the path, and coming back to the path.
You can choose your path, and you have judged harshly in every case I have seen you comment on.
I have judged those who deserve harsh judgement harshly, as those who commit evil against my people. I judged for the good in many cases. I don't think that by pushing people away you have the chance to pull them back in. There is a balance of rebuke and love which must be reached in order to bring peace to this world, and the next world.
PS: I am not making light of the fact that dating outside of Jewish religion is a very bad thing. But at this point he said he has already rebuked him, and his friend did not listen. I am just suggesting that the friendship not be destroyed entirely, just that the friend knows how much it hurts his brothers...