Bonhoeffer stated that mandate (yes, mandate!) more powerfully and succinctly than ever I could. I just wanted to offer a Bible passage that indeed turns his thoughts into a mandate:
A Christian community either lives by the intercessory prayers of its members for one another, or the community will be destroyed. I can no longer condemn or hate other Christians for whom I pray, no matter how much trouble they cause me. In intercessory prayer the face that may have been strange and intolerable to me is transformed into the face of one for whom Christ died, the face of a pardoned sinner. That is a blessed discovery for the Christian who is beginning to offer intercessory prayer for others. As far as we are concerned, there is no dislike, no personal tension, no disunity or strife that cannot be overcome by intercessory prayer. Intercessory prayer is the purifying bath into which the individual and the community must enter every day.
Ephesians 6:10 Finally, be strong in the Lord and in the strength of his might. 11 Put on the whole armor of God, that you may be able to stand against the schemes of the devil. 12 For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places. 13 Therefore take up the whole armor of God, that you may be able to withstand in the evil day, and having done all, to stand firm. 14 Stand therefore, having fastened on the belt of truth, and having put on the breastplate of righteousness, 15 and, as shoes for your feet, having put on the readiness given by the gospel of peace. 16 In all circumstances take up the shield of faith, with which you can extinguish all the flaming darts of the evil one; 17 and take the helmet of salvation, and the sword of the Spirit, which is the word of God, 18 praying at all times in the Spirit, with all prayer and supplication. To that end keep alert with all perseverance, making supplication for all the saints.