Blessed are those who mourn, for they will be comforted.
Taken out of context, this beatitude is often considered to be the mourning associated with death, the loss of a loved one. As far as it goes that is fine. We must comfort those who grieve such loss, but the meaning within the passage as Jesus intended it is much broader. The mourning here is over our lack of righteousness, our sorrow over sin and our inability to overcome it. This mourning is the sorrow of repentance. I was wrong and I am unhappy and wretched because of it. Yet it is one thing to admit to spiritual poverty but it is another to mourn and be sorry for it, not because we got caught and are afraid of punishment, but because it is evil, it is hurtful to us and God because it disrupts our relationship and fellowship with Him. Those who lament and grieve over their own sinfulness will be comforted by the only consolation which can relieve this distress: the free forgiveness of God.
In addition, this mourning involves weeping over the evil in the world, the sins of others, and the reality of judgment and death. Ezekiel the prophet heard the faithful remnant of God described as those who grieved over all the sinful, vile and detestable things that were done in Jerusalem even in God’s Temple (Ezekiel 9:4). So godly mourning involves weeping for those who sin and those who refuse to accept the grace of God found in Jesus alone. We must not get angry with them or despise them but weep and cry for them for their end is going to be far worse than the sorrows of this present life.
Such mourning will receive comfort as we walk in the footsteps of Jesus and accept His will. Ultimately the final comfort awaits the glory of Christ’s return when sin will be no more and as it says in Revelation 21:4 “And God shall wipe away all tears from their eyes; and there shall be no more death, neither sorrow, nor crying, neither shall there be any more pain: for the former things are passed away.” (KJV) Again, only those in the Kingdom of God will enjoy this comfort.