Matthew 5:4

‘Blessed ones, those who mourn, for they will be comforted.'

This is not saying that it is good to be in mourning because the result will be that someone is sure to comfort us. It rather has in mind Isaiah 40 (‘comfort, comfort, my people') where the people of God were mourning over their sin, and God promised that finally He would come to them and encourage and strengthen them, and lift them up. He would take them in His arms like a shepherd and would ‘comfort' them (Isaiah 40:11). In the same way the Anointed Prophet will come ‘to comfort (encourage, strengthen, establish) all who mourn' (Isaiah 61:2) and to give them ‘the oil of joy for mourning' (Isaiah 61:3), words which Jesus must surely have in mind here. These mourners, then, are those who are looking for ‘the consolation' at the hand of the Lord of what are at present a downtrodden remnant who represent the true Israel (Luke 2:25). They are discovering that ‘the Lord is near to those who are broken-hearted and who are contrite in spirit' (Psalms 34:18; compare Psalms 51:17; Isaiah 57:1; Isaiah 66:2). And they have been brought into that blessed state by God so that through it they may be freed from their sins and brought through to enjoying the sustaining presence of God, which was a position that must now with God's encouragement and strength (‘comfort') be constantly maintained. And the result is that both now and in the future life they will continue to be ‘comforted' and made strong (see Isaiah 49:15).

We may include here also the thought found in Psalms 119:136, ‘My eyes shed streams of tears because men do not keep your Law'. Here the mourning is of a godly sort caused by the fact that other men and women do not love God's Law. Those who are His are always constrained in this way. Nothing grieves them more than the failure of men and women to respond to and love God's word. It is the result of the Psalmist himself having become contrite in spirit. For further Old Testament examples of mourning over sin see Ezra 10:6; Psalms 51:4; Ezekiel 9:4; Daniel 9:19.

Thus the idea here is that those who are disturbed about their sinfulness, and about the sinfulness of others, to such an extent that it has caused them to mourn over it and seek Jesus, are like this because they have been truly blessed by God, and the result is that they will have found in Him the encouragement and strength that they need. They are thus seen to have truly repented. And they will therefore also enjoy His Great Comfort, both now and in the Last Day (Isaiah 40:1; Isaiah 49:13; Isaiah 51:3; Isaiah 51:12 etc.).

So we are here already seeing the kind of people who make up Jesus' disciples. They are humble and lowly, and aware of sin. And they have recognised in Jesus the One Who has come to save His people from their sins (Matthew 1:21). And that is why they are seen as being those who have been blessed by God.