Luke 6: “For no good tree bears bad fruit, nor again does a bad tree bear good fruit,  for each tree is known by its own fruit. For figs are not gathered from thornbushes, nor are grapes picked from a bramble bush.  The good person out of the good treasure of his heart produces good, and the evil person out of his evil treasure produces evil, for out of the abundance of the heart his mouth speaks.
The first word of the Scripture quote above is “for”. This means that what Jesus said is a direct result of what He spoke before He said that. It most likely goes all the way back to verse 27. From verse 27 to 42 Jesus has said that we are to love our enemies, not judge others, and deal with our own sins before we focus on the sins of others. And then Jesus says “For no good tree bears bad fruit …” This means that the specific fruit Jesus is talking about is those things.
Jesus is not saying that His disciples will never sin once they know Him. If we were to maintain this we would be testifying that we are not Christian at all (I John 1:8). But Jesus is saying that when a person comes to know Him there will be a change in his heart that shows itself in changed behaviour. He says nothing here about finding ourselves in a church meeting several times a week or getting so busy in formal church things that we have no time for family or neighbours. The fruit He mentions have to do with interpersonal relationships.
People who know Jesus Christ are going to treat other people differently than they did before they knew Him. The enemies they used to hate and work against and gossip about they will now love and seek to help. People they used to enjoy condemning as great sinners they will now mourn over and seek to win to Christ through prayer and Gospel witness. They once held grudges but now they have found the desire and ability to forgive those who have done them harm. They will no longer be greedy but giving instead. Because they now know Christ they will be able to lead others into an awareness of the claims and requirments of the Gospel. And they will constantly be aware that they have sin that they need to pay attention to in their own hearts, minds and actions. They know that their own sins need to be dealt with before they start pointing accusing fingers at others.
How do we measure the fruit of the Holy Spirit in our lives? The fruit of real conversion will always, always, always include improved relationships with others. This will especially show with other believers. We can become so prone to saying we are saved because we read our Bibles, go to church, put money in the offering plate, get involved in ministry. Nothing wrong with any of those things. But any pagan can do them (See Luke 18:9-14). Jesus doesn’t even hint at these things. Eliminate those things out of the proof you would offer to show that you are a believer and focus instead on how well you get along with other people. Are you bearing good fruit now? At the end of this section Jesus mentions another piece of the good fruit of a real encounter with Christ, but we’ll get to that next week. For now we camp here. The good fruit that Jesus focuses on as evidence of real faith is our attitudes and behaviour toward other people. And if we are honest, we will see that we all need to work hard at improving those relationships.