Jesus has a counter-cultural view of what it means to be truly happy (read part 1, part 2, part 3)
Blessed are the peacemakers, for they shall be called sons of God
To be a peacemaker is not the same thing as wanting a bit of peace and quiet. It is not doing "anything for an easy life". That attitude is essentially selfish. To be a peacemaker requires the selflessness already described earlier in this chapter. Making peace will often be difficult. It may require some conflict to get to the heart of the issue, not pretending that the conflict isn't there because that is more comfortable. It may require words that are hard to say and receive instead of brushing things under the carpet. Jesus says peacemakers will be called sons of God. THE Son of God came on a mission to bring peace between us and God. It involved him loving people who everyone hated, confronting religious leaders, violating social conventions, being hated by others and ultimately dying a brutal death on a cross. The peace that his death purchased for us should motivate a pursuit of peace with others.
Blessed are those who are persecuted for righteousness' sake, for theirs is the kingdom of heaven. Blessed are you when others revile you and persecute you and utter all kinds of evil against you falsely on my account. Rejoice and be glad, for you reward is great in heaven, for so they persecuted the prophets that were before you.
We should not be surprised to be persecuted for being a Christian. It could take a variety of forms, but the prophets were persecuted, Jesus was persecuted and he said we would be as well. A life marked by the characteristics described in this chapter will attract persecution because it in itself is a criticism of the life lived outside of Jesus. Recognising our spiritual poverty is a criticism of other's pride. Mourning over our sin points out that there is such a thing as sin. Being meek causes selfishness to stand out. Being hungry and thirsty for righteousness is a comment on the other things people hunger and thirst for. Purity of heart highlights the impure. Making peace can cause conflict with those who don't want to.
But not being surprised when persecution comes is a lot different to describing it as being blessed! True happiness can be found through persecution?! Jesus tells us to rejoice and be glad because of our great reward in heaven. Persecution makes us long for our future, it reminds us not to get too comfortable, it makes us more aware of our spiritual poverty, more mournful over our sin, more humble, more desperate for God.
It's not being happy about the persecution itself, but the presence of that persecution drives us to the source of true happiness - God. We might think that a life free from persecution would be happy, but there is far more danger that we would then take our eyes off God. We tend to look at the immediate circumstances instead of the big picture and so persecution seems bad. But:
...we do not lose heart. Though our outer self is wasting away, our inner self is being renewed day by day. For this light momentary affliction is preparing for us an eternal weight of glory beyond all comparison, as we look not to the things that are seen but to the things that are unseen. For the things that are seen are transient, but the things that are unseen are eternal. (2 Corinthians 4:16-18)