I have frequently heard Christian speakers talk about how God doesn't want us to live in pain or with depression. If we turn it all over to Him, he will heal us and make us whole. As if some of these illnesses are our own doing and we should just try harder to get closer to God. We must be doing something wrong if we aren't healed. Many people get more discouraged by this kind of talk, and some may even fall away because they believe the lie that they, themselves, are the true cause of the problem.
That is such a hurtful message to so many people. God often puts us in difficult situations, emotional and physical, so we can cling to him and help others. Yes, we often bring depression and stress-related illnesses on ourselves, but not always.
When Jesus was walking to the temple one day, he passed by the Pool of Bethesda. People believed that this pool was touched occasionally by the wings of angels, and that whomever could get into it first when the water was disturbed would be healed. John 5:3 says "Here a great number of disabled people used to lie -- the blind, the lame, the paralyzed." Jesus saw one man who had been an invalid for thirty-eight years, and he asked the man if he wanted to be healed. The man said yes, and Jesus told him to pick up his mat and go home. The man was cured at once.
Could you imagine being the person who was lying next to this man? Why had Jesus selected him and not someone else? Why did he not speak the words and heal every person at the pool? It's easy for us to give reasons such as 'they didn't believe enough' or 'they didn't deserve it'. But we weren't there, and John didn't give any explanation. Jesus healed this one to make a point, but that doesn't mean he didn't love or care about the others.
There are many great saints in God's kingdom who deal with physical and emotional disabilities. God doesn't heal their bodies, but he has healed their hearts and he's put them into situations where many can learn from their examples. They existed even in Biblical times; look at the injuries of Jacob, the thorn in Paul's side, the suffering of Job, and the depression of Jeremiah.
While God could heal them in a second, sometimes he choses not to. They will have whole and perfect bodies when they get to heaven.
If you don't have any physical or emotional ailments, or if you have been healed from them, please be thankful and praise God. But don't look down on others who suffer. They may be blessed with this 'gift' in order to be an example of faithfulness through adversity, and they may be just the example or help that someone else might need. Don't insult them by suggesting that they should just pray harder...you will be a clanging cymbal, just as Job's friends were.