He will wipe away every tear from their eyes, and death shall be no more, neither shall there be mourning, nor crying, nor pain anymore, for the former things have passed away.
Revelation 21:4
There is a question that has plagued many Christians since they first learned of Heaven and Hell. When they realize that some family and friends may face the eternal wrath of God, they wonder how they can spend an eternity in Heaven where there are no tears or sadness if they will know of their loved ones' fate. If your mother goes to Hell, and you go to Heaven, how will you be eternally happy when you know she is in eternal torment? Many have attempted to answer this question. Some attempts result in heresy, such as universalism (which teaches that either everyone will be saved or that Hell is a temporary place of purification for those who haven't accepted Christ before going to Heaven). Within orthodox Christianity, though, there are primarily three theories, each of which has a Scripture basis (note that the names I give them are not official; I have given them titles for convenience).
Purged Memory Theory
For behold, I create new heavens and a new earth, and the former things shall not be remembered or come into mind.
Isaiah 65:17
One theory is that God will supernaturally remove from our minds any thoughts of those whom we once loved. Basically, the utter removal of the lost from the presence of God in Hell will allow us to forget them entirely, and therefore be perfectly happy in God's presence.
Pros: In this theory, we have no sorrow whatsoever, even while our hearts would remain perfectly tender to those who are in Hell if we knew of them (cf. Isa. 43:18).
Cons: It does seem somewhat strange that we would have further imperfect knowledge in Heaven. As well, if we didn't know that anyone was in Hell, would we not have imperfect, illogical understanding of our own salvation? We would either have to think that we are everyone who ever existed, thus believing a form of universalism, or forget that were we ever saved from Hell to begin with.
Overwhelming Joy Theory
You make known to me the path of life; in your presence there is fullness of joy; at your right hand are pleasures forevermore.
Psalm 16:11
Basically, this theory states that we will be so incredibly filled with intense joy, happiness, and delight in the glorious presence of God that there will be no room for sorrow over the condemned. While we will still realize that there are lost people suffering the eternal wrath of God, we will be so intoxicated by the wonderful greatness of being with God that we will hurt over it. Joy will fill us in our knowledge that God has been so gracious and merciful to us.
Pros: This theory recognizes that God is ultimately wonderful, and His presence alone can vaporize all sorrow (cf. Isa. 51:11; Rev. 7:17). It also preserves full knowledge of God's plan of salvation.
Cons: If it can be said there are any cons to this theory, one might object that this does not fulfill the whole design of God. After all, a believer's highest source of joy should be the glory of God, and we know from Scripture that God's just judgment brings Him glory (see Exodus 14:4 and cf.). Thus, this theory effectively neutralizes the possibility of receiving joy from a major contribution to God's glory (this objection could also be made towards the purged memory theory).
Joy in Justice Theory
After this I heard what seemed to be the loud voice of a great multitude in heaven, crying out, "Hallelujah! Salvation and glory and power belong to our God, for his judgments are true and just; for he has judged the great prostitute who corrupted the earth with her immorality, and has avenged on her the blood of his servants." Once more they cried out, "Hallelujah!
The smoke from her goes up forever and ever."
Revelation 19:1-3
This relatively controversial theory says that we will not be sorrowful in Heaven because we will indeed rejoice at seeing God finally administer the justice of His holy wrath on the wicked. While we may love these people throughout our lives, our love for God upon seeing Him will fully overcome it, and we will be so thrilled at the concept of seeing God finally vindicated in His holiness that we will have no tears left for the unrepentant. In this theory, our joy in the glory of God will climax in triumph over our compassion for sinful, unrepentant man.
Pros: This theory emphasizes that man's greatest source of joy is and by right ought to be the glory of God Almighty. It is very evident throughout Scripture that God is glorified by His just and holy judgment on rebellious sinners. It is also evident throughout Scripture that God's glory (and our rejoicing in it) is the aim of God's plans (cf. Deut. 42:33; Ps. 104:35; Rev. 16:16; 18:20).
Cons: Many people find this theory unsavory, feeling that it belittles the love of God and our commanded love for others. They think it is tasteless at best or immoral at worst to rejoice at the wrath of God unleashed on other people, even if they do deserve it.
The End
I am not here to tell you for certain which of these theories, if any, is correct. It is possible that the truth is even a combination of one or more of these. Nevertheless, we can rest assured that we will have no more tears when Jesus comes and makes us His bride. He is so loving and so wonderful; He will make sure we never have reason to mourn for all of eternity. Let us wait in hope and joy for His coming!