John Piper has given us an extremely helpful book whether we ourselves are battling the darkness of depression, or someone close to us is. Please check out my full book review of When The Darkness Will Not Lift by clicking here.
“This is the rock where we stand when the dark clouds gather and the floods lick at our feet: justification is by grace alone (not mixed with our merit), through faith alone (not mixed with our works) on the basis of Christ alone (not mingling His righteousness with ours), to the glory of God alone (not ours).”
“Where should you start? Start at the easiest place for those in darkness. Start with despair. Despair of finding any answer in yourself. I pray that you will cease from all efforts to look inside yourself for the rescue you need. I pray that you will do what only desperate people can do, namely, cast yourself on Christ.”
“You cannot isolate the spiritual from the physical for we are body, mind and spirit. The greatest and the best Christians when they are physically weak are more prone to an attack of spiritual depression then at any other time and there are great illustrations of this in the Scriptures.”
“It will be of great advantage to the struggling Christian to remember that seasons of darkness are normal in the Christian life.”
“One of the reasons God loved David so much was that he cried so much. … It is a beautiful thing when a broken man genuinely cries out to God.”
“Faith is sustained by looking at Christ, crucified and risen, not by turning from Christ to analyze your faith. … Paradoxically, if we would experience the joy of faith, we must not focus much on it. We must focus on the greatness of our Savior.”
“It follows from this that we should all fortify ourselves against the dark hours of depression by cultivating a deep distrust of the certainties of despair. Despair is relentless in the certainties of its pessimism. But we have seen again and again, from our own experience and others, that absolute statements of hopelessness that we make in the dark are notoriously unreliable. Our dark certainties are not sureties. While we have the light, let us cultivate distrust of the certainties of despair.”
“Instead of only saying, ‘Just do your duty,’ we must say…that joy is part of your duty. The Bible says, ‘Rejoice always’ (1 Thessalonians 5:16). And in regard to the duty of giving, it says, ‘God loves a cheerful giver’ (2 Corinthians 9:7). In regard to the duty of service, it says, ‘Serve the Lord with gladness’ (Psalm 100:2). In regard to the duty of mercy, it says do it ‘with cheerfulness’ (Romans 12:8). In regard to the duty of afflictions, it says, ‘Count it all joy’ (James 1:2). We simply water down the divine command when we call someone to half their duty.”
“In dealing with our sin we can make two mistakes. One is to make light of it. The other is to be overwhelmed by it.”
“If we want the joy of seeing and savoring God in Christ, we must not make peace with our sins. We must make war.”
“Sometimes the darkness of our souls is owing in some part to the fact that we have drifted into patterns of life that are not blatantly sinful but are constricted and uncaring. … Unconsciously we have become very self-absorbed and oblivious and uncaring toward the pain and suffering in the world that is far worse than our own.”
“Paradoxically, depressed persons may say that they must care for themselves and cannot take on the problems of the world, when in fact part of the truth may be that their depression is feeding on the ingrown quality of their lives. … Joy in Christ thrives on being shared. That is the essence of Christian joy: it overflows or dies.”
“To pray for ‘things’ without a heavenly end in mind is close to idolatry. Use your material wealth with holy fear, dear saint, lest earth should rob heaven, and your temporal enjoyments endanger your heavenly interests. … 
Craig T. Owens 