This is a hard word to teach kids! Take a moment and think about how you would define this word so a seven year old could understand it.
It is a big word with big meaning, and doesn't have many words that rhyme with it easily - all reasons you won't find it in many kids' Sunday school songs. You might have said to yourself, "I wouldn't try to define that word for a kid, it is too complicated." In my own experience I have run into many dead ends when trying to explain this word and concept to children. It seems their attention span runs out quicker than my explanation!
I often pose difficult questions in the framework I just gave you. The thought in my mind is that if I can explain something to a child, then I can explain it to anyone. When explaining things to kids it is important to boil a thing down to it's most important pieces in order to deliver it in the most concise manner.
You might not think that the book of Romans is concise; rather, the word detailed might come to mind, maybe even methodical. But I am beginning to believe that it was Paul's intention was to explain righteousness in the most concise and profound way he could. At the end of the book, one should be thoroughly informed on this concept, and for good reason.
Righteousness is something I think most humans desire, and is bestowed or claimed because the beholder has met a standard. There are many standards offered throughout the world, most notably, the standard presented in the 10 commandments. Righteousness is worthy of our consideration because I think in some way everyone is already thinking about it and pursuing it. But Paul is making the carefully crafted case that we will not find righteousness in anything other than faith in Christ. It can not be bestowed or claimed by anything or anyone Earthly.
Moreover, righteousness is the only thing that can deliver us from perishing apart from God. It is at the core of our status before God, and the need Jesus came to fulfill. Hopefully that truth pushes the need to understand and explain righteousness to the forefront of our minds. The next time I have a chance to explain righteousness to a child, I would like to say that it is like a fine robe that we need to enter into Heaven one day, and Jesus' will let us wear His if we ask him.
In His Steps,