Righteous

My little children, these things I write to you, so that you may not sin. And if anyone sins, we have an Advocate with the Father, Jesus Christ the righteous.

1 John 2:1

Absolute zero in minus 459.67 degrees on the Fahrenheit scale - that sounds pretty precise, but no one has ever been able to ever get something that cold, because it is the total absence of all heat. It would make atoms completely stop moving. 

To be totally free from sin is to be righteous. Living in a sinful world with all the lusts and evil thoughts that abound here, righteousness is a concept that is  approached rather than obtained. The Christian life is the process of working with God to crucify the sinful human nature by working with God to live righteously (Galatians 5:24-25). This may be an impossible-to-reach goal this side of heaven, but each believer is encouraged to get as close to it as he can.

Christ is the only one who is truly Righteous. He never had a bad attitude, flew off the handle, made poor choices, nor snapped under pressure. Everything He thought, felt, or did was totally right. As God, He could not do wrong, but even in His human capacity, He chose to be sinless.

Believers become more and more righteous as they progressively conform to the image of God's Son (Romans 8:29). It's not easy to keep one's thoughts on everything that is true, noble, just, pure, and lovely (Philippians 4:8), but Jesus certainly did. When Christians have the mind of Christ (2 Corinthians 2:16), they are able to do that also. They begin to be righteous even as He is Righteous.