And you will know that there is nothing easier and sweeter or more manageable than these commandments. Return you who walk in the commandments of the devil, in hard and bitter and wild immorality. And do not fear the devil, for there is no power in him against you, for I will be with you, the angel of repentance, who am Lord over him. The devil has fear only, but his fear has no strength. Do not fear him, and he will flee from you.
So the early Christians for sure believed that these were God's new law, the new commandments. Don't let anybody fool you. Don't let Satan or your flesh. The Sermon of the Mount is for today. It's God's new commandments for His people now. It's expected of us. It's for you, and it's for me.