For those who are God's people through faith in Jesus, God is at work in us for holiness. We are "predestined to be conformed to the image of his Son" (Rom 8:29) and THIS is why "all things work together for good" (Rom 8:28) to those who are called by God and love God (i.e. the church). God is working all things, even bad things like suffering, to make his people look like "his Son," Jesus Christ. Therefore, God is concerned about our holiness. So you could say that there are times when God makes us sad in order to make us holy. That is, he leads us through suffering as we go through sanctification.
Yet God also cares about the happiness of his people. Not in the flippant way that so many people imagine. For instance, the idea that God would never lead his people through suffering - that must be the devil in charge (as if God were on vacation and forgot to take that suffering away) - is just unbiblical theology. To say that God cares about our happiness more than anything else is not true to Scripture, for first on God's priority list is the display of his glory. And yet God is working, not just for our holiness, but for our eternal happiness in him. See the difference? It is unbiblical to say that God puts our happiness first, and therefore would never let us suffer at all. But it is biblical to say that God will lead us through suffering knowing that our eternal happiness is on the other side.
See how these themes (God's glory, our holiness and our happiness) play out in just one passage of Scripture:
Now to him who is able to keep you from stumbling and to present you blameless [our holiness] before the presence of his glory with great joy [our happiness], to the only God, our Savior, through Jesus Christ our Lord, be glory, majesty, dominion, and authority, before all time and now and forever [God's glory]. Amen. Jude 24-25, ESVGod is glorifying himself in his people's eternal holiness and happiness, and uses even sorrow to do it. So, God sometimes makes us sad to make us holy and happy.
This is pictured very beautifully in John 11. Mary and Martha, sisters who are friends of Jesus, send him word that Lazarus, their brother and Jesus' friend, is sick. Jesus could have hurried to Bethany to heal Lazarus. But the Bible says, "Now Jesus loved Martha and her sister and Lazarus. So, when he heard that Lazarus was ill, he stayed two days longer in the place where he was" (11:5-6). Did you catch the "So"? He loved them, SO he waited around and did not heal Lazarus. He loved them SO he let Lazarus experience the pain and sorrow of death. He loved Mary and Martha SO he let them experience the sadness of seeing their brother die. Does this make sense?!
But we know the rest of the story. After Lazarus was dead, Jesus came and raised him from the dead. He knew all along what he was going to do. He also knew that it was better for them to go through some temporary sadness and experience eternal joy (by believing in Jesus as they saw his glorious work) than it would be for him to just remove the sadness and heal Lazarus. Did you get that? Jesus knew it would be better - ultimately and eternally - for the people he loved if he allowed them to go through some sorrow. The joy on the other side of the sorrow was better than any joy they would have had from being spared the sorrow!
Jesus is also concerned about God's glory. He said that Lazarus' illness was "for the glory of God, so that the Son of God may be glorified through it" (v4). In other words, God is going to let Lazarus get sick and die, and let his sisters experience this loss, so that God would be glorified through Jesus. God's glory is more important than our health! So, in all of this we see that God is working for his glory (v4) and, because he loves his people (v5), he is also working, in the same event, for their eternal happiness ("so that you may believe," v15). A lot of factors going on here!
Jesus said to Martha, "Did I not tell you that if you believed you would see the glory of God?" (v40). They rolled away the stone and Jesus prayed. "Father, I thank you that you have heard me. I knew that you always hear me, but I said this on account of the people standing around, that they may believe that you sent me" (v42). And then he raised Lazarus from the dead.
This is remarkable because of the resurrection of the dead, but also because we are given a glimpse into God's reason for the sorrowful event! God had a good reason for the sadness he allowed in his people. So that he would be glorified (v4) and so they would believe (v15, 40, 42), and by believing be eternally holy and happy. God made them sad so that he could make them happy. Forever!
When God allows sorrowful things to come into our lives, we are not always shown the reasons. But Scripture teaches us that God is good, and can be trusted. He is at work, even in suffering, to glorify himself, and to make us forever holy and happy in him. Hallelujah! Be encouraged as you face sadness. It is not in vain. Trust God, who gave his Son to the death of the cross for our sins, and raised him from the dead for our eternal salvation. Believe on Christ and walk through the sorrow. There is joy on the other side!