Nicodemus was an expert in what we would now call "Old Testament" scripture, including the law as well as the myriad of Jewish oral traditions and Pharisaical practices. What I’m saying is that Nicodemus was an intelligent, religious man who worked very hard at his faith.
Nicodemus was also smart enough to recognize that Jesus had something mysteriously profound to offer regarding spiritual insight. So Nicodemus approached Jesus one day. John chapter three shares this encounter for us. Nicodemus offers a respectful greeting… Jesus responds with a statement about being born again. Nicodemus responds dumbfoundedly… Jesus responds with further statements about being born again. Nicodemus responds again dumbfoundedly… Jesus responds with the verse held up by the guy in the rainbow wig at the football games. Basically, Jesus explains the necessity of conversion, the process of conversion, the purpose of conversion, the passion of conversion, and how conversion is possible. And Nicodemus doesn’t get it.
Now Jesus is dumbfounded. He is amazed that Nicodemus doesn’t understand the idea of conversion. "You are Israel’s teacher," he said to Nic, "and you don’t understand these things?"
I don’t think Jesus was slamming Nicodemus’ intellect. I do think Jesus was implying that Nicodemus, with all of his learning and training, should have understood these things! Nicodemus had read the Scriptures! Nicodemus had studied and trained under the brightest of Israel’s religious scholars and rabbis. He taught people everyday to live for God and obey the commands. And Jesus is dumbfounded that Nicodemus didn’t understand how God wanted to work in changing people’s lives.
I think one of the difficulties the word “conversion” has for our Western culture is that it makes salvation a moment, not a process. This has led to what many call “cheap grace”; that people pray a prayer or intellectually assent to a moment of salvation so they can gain some assurance of fire insurance, and then go on with their lives.
Conversion is actually quite a good word because it suggests that something has changed; but what is difficult is defining or pin pointing just what has changed.
I suppose simply, because Jesus is God incarnate and if we have seen Jesus then we have seen the Father, then when we turn from selfish ambition (essentially blaspheme of the Holy Spirit) and become a follower of Jesus (Jesus is now master not us) then a turning, or converting from one worldview has happened. The question then becomes one of actions here and now on earth. How does conversion tie in with our actions?
I like how Dallas Willard defines grace in his book “The Great Omission”: “Grace is opposed to earning, not to effort. Earning is an attitude. Effort is an action.” So many people say that we are saved by faith and not works and their unchanged lives apparently prove it…but grace does not remove effort, it removes earning. Conversion must change our lives in that we follow Jesus which takes effort.
The people of the OT trusted in Yahweh and He came through on many occasions! In fact, some suggest that salvation to people in the OT had almost no connection to a heavenly afterlife, but rather a here-and-now salvation from enemies, empty wombs, and questionable promises. They put their faith (trust) in the One True God instead of other gods (well, not always, but ultimately they did I suppose).
So…what does it mean to be converted? Well, Dietriech Bonhoeffer would say it absolutely must include discipleship, for, “cheap grace means the justification of sin without the justification of the sinner” (Cost of Discipleship p46). Salvation must be understood as something which has happened, is happening, and will happen…and we have too often focussed on the first and third but not the second.
Ok…now I’m rambling…