According to Matthew 5:1–12, Jesus delivered the beautiful Beatitudes during His Sermon on the Mount. In this series of nine sentences, an unlikely group of people are referred to as blessed: those who are poor in spirit, those who mourn, those who are meek, those who hunger for righteousness, and those who are merciful. Those who are part of the kingdom of heaven are all blessed.
The passage indicates that all men are sinners since only God is perfect. Thus, keeping the Law externally is not a sufficient criterion of righteousness. A clear message of the Sermon on the Mount is that the Law is insufficient to save a soul. The Law cannot forgive sins, but it serves as a guide for lost sinners to find Christ, in Whom they can find life, light, hope, and salvation.
Regardless of its primary audience, the Sermon on the Mount is not intended for unbelievers, but rather for Jews as well as Gentiles, which can only be achieved through the power of the indwelling Holy Spirit – when a Christian's inner heart has sacrificed self and only lives for Christ.

Dear Heavenly Father, the Sermon on the Mount contains many truths that can be learned from it, and I thank You for it. The King of Israel, Jesus, will one day be crowned as their Messiah. Thank You for sending Him as my Saviour, who paid the price for my sins and broke the power of sin and death. Thank You for indwelling me with the Holy Spirit of God and for making a new heart for me with Your grace. 
In Jesus's name I pray. Amen.