“Right” is whatever conforms to God's moral character.
Because He rules the world in righteousness, it is inconceivable that He would not reveal His righteous requirements to those He has created in His image to love and obey Him.
I Yahweh speak the truth,
I declare what is right (Isa 45:19).
“Right” = whatever has been appointed by God to be acknowledged and obeyed by men.
“Righteousness” is the word used to refer to the sum total of the requirements of God.
“John came to you in the way of righteousness” (Matt 21:32).
“Blessed are those who hunger and thirst for righteousness, for they shall be satisfied” (Matt 5:6).
“Seek first His kingdom and His righteousness. . . .” (Matt 6:33).
God ensures that men know what righteousness requires of them in two ways.
1) God has created us so that we are able to know what righteousness requires without being told.
“For when Gentiles who do not have the Law do instinctively the things of the Law, these, not having the Law, are a law to themselves, in that they show the work of the Law written in their hearts, their conscience bearing witness and their thoughts alternately accusing or defending them” (Rom 2:14-15).
2) We encounter our inner sense of what is right again — particularly in God’s “greatest commandments.” This is most immediately evident in the second greatest commandment, which builds on the natural inclination in every human life to be treated kindly and well. “You shall love your neighbor as yourself” (Matt 22:39).
The great and foremost commandment does the same: “You shall love the Lord your God with all your heart and with all your soul and with all your mind. This is the great and foremost commandment” (Matt 22:37-38; Deut 6:5). It draws on our conscience’s attraction to what is good and to its witness to God’s being: “. . . That which is known about God is evident within them; for God made it evident to them” (Rom 1:19).
These commands, the Ten Commandments (called God’s “testimony” and written by Him [Exod 31:18]), and the many derivative biblical commands that prohibit or require specific behavior are recognized as “apodictic” — they are evident “from the saying” or “self-evident.” When we hear them we know that they are right. We do not need argument of proof to be convinced that they are declarations of what righteousness is.
Jesus’ call to righteousness is inseparably linked to keeping the Law God gave:
“Do not think that I came to abolish the Law or the Prophets; I did not come to abolish, but to fulfill. For truly I say to you, until heaven and earth pass away, not the smallest letter or stroke shall pass from the Law until all is accomplished. Whoever then annuls one of the least of these commandments, and teaches others to do the same, shall be called least in the kingdom of heaven; but whoever keeps and teaches them, he shall be called great in the kingdom of heaven.”
“For I say to you that unless your righteousness surpasses that of the scribes and Pharisees, you not enter the kingdom of heaven” (Matt 5:17-20).
(Spotlight 3, Lesson 10 in Doctrine 101: Learning about God)