Matthew 7:17-20
17 A good tree produces good fruit, and a bad tree produces bad fruit. 18 A good tree can’t produce bad fruit, and a bad tree can’t produce good fruit. 19 So every tree that does not produce good fruit is chopped down and thrown into the fire. 20 Yes, just as you can identify a tree by its fruit, so you can identify people by their actions.
Of course, though, you can’t always judge a book by its cover. In fact, in other verses, Jesus condemns the Pharisees for not seeing the change of heart in groups traditionally thought of as sinful, like tax collectors.
Matthew 21:31
Which of the two did the will of his father?” “The first,” they answered. Jesus said to them, “Truly I tell you; the tax collectors and prostitutes are entering the kingdom of God before you.
But how do we reconcile these opposing sections? Well, the tax collectors like Zaccheus really did have a change of heart expressing good fruit. In that case, he was producing good fruit, and the same idea applies elsewhere.
Luke 19:1-10
(verse 1) Jesus entered Jericho and was passing through. 2 A man was there by the name of Zacchaeus; he was a chief tax collector and was wealthy. 3 He wanted to see who Jesus was, but because he was short he could not see over the crowd. 4 So he ran ahead and climbed a sycamore-fig tree to see him, since Jesus was coming that way.
5 When Jesus reached the spot, he looked up and said to him, “Zacchaeus, come down immediately. I must stay at your house today.” 6 So he came down at once and welcomed him gladly.
7 All the people saw this and began to mutter, “He has gone to be the guest of a sinner.”
8 But Zacchaeus stood up and said to the Lord, “Look, Lord! Here and now I give half of my possessions to the poor, and if I have cheated anybody out of anything, I will pay back four times the amount.”
9 Jesus said to him, “Today salvation has come to this house, because this man, too, is a son of Abraham. 10 For the Son of Man came to seek and to save the lost.”
The good fruit is mainly about how much you wish to live your life and the attitudes that you showcase. It can go a long way to ensuring that you live a good life.
Like I said in my previous comment, it doesn’t take long to spot people who are not following the will of God even if they pretended to. Their actions and lifestyle will tell you who they are.