How can Heaven exist if we know that people in Hell will suffer? Suppose for the following scenario that both the Christian Heaven and Hell exist.

My mother is a good Christian and loves me dearly.

I am an atheist, and will therefore go to hell upon death. [If you don't agree that I will go to hell for being an atheist, simply consider me a sinner who will go to hell.]

When my mother dies she will go to Heaven.

How can my mother possibly experience eternal happiness with the knowledge that her beloved son is being tortured for eternity?

Note: I do not know the originator of this argument. I know that Matt Dilahunty has made it before, though do not know if he came up with it. I ask because I think it poses a valid inconsistency and I would to hear the Christian response.
Short answer: We don't know for sure.  The rest of this answer explores various "Christian answers", but the conclusion is "we don't know for sure".



This is a question that I struggled with when I was an atheist, and it's a question that Christians have grappled with and that has never been answered in a way that would have been intellectually satisfying to me as an atheist.  There are several attempts to give answers, some okay, some blatantly out of line with what we do know of Heaven.


Some have theorized that we will not know of the suffering of the lost.  That God may remove that knowledge from us.  This would be inconsistent with the nature of God, and also 1 Corinthians 13:12, which teaches us that we will have increased knowledge, not decreased.
Some have theorized that Heaven is so wonderful that the thought of our loved ones will seem insignificant.  That hardly fits with the Christian message of Agape (selfless) love being the ultimate expression and reflection of God.


Christianity.ca adds this:


  A second possibility boldly suggests that this awareness will be a
  cause for joy and praise rather than pain. Shocking though it may
  sound, this position has been defended by many theologians including
  Thomas Aquinas, Jonathan Edwards and, more recently, J. I. Packer. As
  Edwards put it, the redeemed “will not be sorry for the damned; it
  will cause no uneasiness or dissatisfaction to them; but on the
  contrary, when they have this sight, it will excite them to joyful
  praises.”
  
  Grisly though this may sound, it has some impressive scriptural
  support. The imprecatory psalms (such as Psalm 139:21-22) seem to
  anticipate with great relish the demise of the wicked. And one might
  reasonably infer that the saints who plead for their blood to be
  avenged (see Revelation 6:10) will extract satisfaction once this
  judgment on “the inhabitants of the earth” is underway.


I don't buy that interpretation, either.

Alwaysbeready.com says this:


  The thought of being apart from your friends and family who do not
  know the Lord is a heart wrenching thought. But God assures us in His
  Word that in Heaven our joy will be absolutely full.
  
  Psalm 16:11 says, “In Thy presence is fullness of joy; in Thy right
  hand there are pleasures forevermore.”
  
  All who go to Heaven will experience “fullness of joy.”
  
  Revelation 21:4 tells us, "He [God] shall wipe away every tear from
  their eyes; and there shall no longer be any death; there shall no
  longer be any mourning, or crying, or pain; the first things have
  passed away."
  
  Quoting C. S. Lewis again, "If you are concerned about your loved
  one's that won't be in Heaven, the most irrational thing you could do
  if you are truly concerned about those on the outside is to remain
  outside yourself."
  
  The best thing you could ever do is to make sure you’re going to
  Heaven and then do all that you can to help wake up your loved ones!


Finally, this nugget from Ray Comfort is, perhaps, both the least intellectual, but closest to my belief:


  "How can people be happy in Heaven, knowing that their unsaved loved ones are suffering in Hell?" Those who ask question such as these
  fall into the category of those who asked Jesus a similar question.
  They said that a certain woman had seven consecutive husbands, whose
  wife will she therefore be in Heaven (Mark 12:23)? Jesus answered them
  by saying that they neither knew the Scriptures nor the power of God.
  The unregenerate mind has no concept of God's mind or His infinite
  power. If God can speak the sun into existence; if He can see every
  thought of every human heart at the same time; if He can create the
  human eye with its 137,000,000 light-sensitive cells, then He can
  handle the minor details of our eternal salvation.


As for me, personally, my answer would be close to what Mr. Comfort stated.  Quite frankly, I don't know for sure.. And neither does anyone else.  

But what I do know is that for the longest time, I thought that God was a lie.  I thought that Jesus was an invisible friend for weak-minded fools that were too weak to face life without some invisible friend helping them along.  I thought that the Bible was a bunch of hooey, made up by a bunch of creeps that wanted to manipulate people for their own gain.  

And I was wrong.  God has proved Himself to me in ways that I would have never imagined.  He has earned my trust.  His word is trustworthy, and if His word says we'll be happy in Heaven, even with the knowledge of our loved ones suffering, I trust Him.  I trust His word.



I know that the above is not going to be satisfying on any level to an atheist.  I realize what it sounds like, but for some questions, there are no easy answers.  Sometimes the only correct answer is "we just don't know for sure".  But to make it a "Christian answer" we have to allow for that component of faith that says that even if we don't know, we trust in God.