Today's Gospel reading from Matthew 5 was Jesus' Sermon on the Mount, giving us the Beatitudes. The 6th, 7th, and 8th Beatitudes also made up the Communion antiphon. Here they are.
Blessed are the clean of heart, for they will see God.
Blessed are the peacemakers, for they will be called children of God.
Blesses are they who are persecuted for the sake of righteousness,
for theirs is the Kingdom of heaven.
Just these three declarations of blessedness alone show how we are to live and what our rewards will be. We must be solely concerned about living for the sake of God and not about whether we go against the world or not.