A good person brings good things out of the good stored up in their heart, and an evil person brings evil things out of the evil stored up in their heart. For the mouth speaks what the heart is full of.
Jesus’s Sermon on the Plain is like a mini, condensed version of his Sermon on the Mount (Matthew 5-7; link above is Luke 6:17-49, the Sermon on the Plain). In Jesus’ teaching, as well as the teaching of the rest of scripture, people are known for what they do and say. We can’t help but express what’s in our hearts. And that can be a scary thought if our hearts are full of what isn’t good, if we let our hearts be corrupted by the evil of sin.
Some people don’t understand this well, and somehow think that words don’t matter, and that people can change at the snap of a finger. That is neither true to scripture, nor to life. Our actions oftentimes begin with our words. We need grace as in kindness and generosity, and patience as in forebearance (putting up with each other at times) in love, along with truth telling. Truth telling (as Scot McKnight points out in his helpful book, The Heaven Promise: Engaging the Bible’s Truth About Life to Come) is something of central importance in the ethic of love in the kingdom of God, as taught by Jesus.
Of course we need the life-changing power of the gospel to begin the change in Jesus into likeness to him. And nothing less. Even though people do change themselves in others ways, and that can be for good. But the change in Jesus is the change that will continue beyond this life.
We are in a struggle in this life against the world, the flesh and the devil, one that will not let up in intensity, I don’t believe, even while hopefully in and through Jesus we are progressing together toward maturity in him. We can’t play with sin. Sin wants to have us, and to have its way in us, but instead through God’s grace in Jesus, we must learn to master it (Genesis 4; Romans 6). We are told to put to death the misdeeds of the body, since we are not “in the flesh, but in the Spirit” (Romans 8).
And we need discernment, which I find sadly lacking today. People, and sadly enough many of us Christians along with them can get all taken up with those who put on an air of greatness to get control. This happens in churches, and is happening right now in the political world in this year’s presidential campaign. There is a huge difference between a flawed candidate, and one who may actually be dangerous. We need discernement. And sometimes the people who purport to have the most discernment seem to have the very least. I think of some who “prophesy” and claim to be Spirit-filled. Beware or at least wary of such. Always go back to the word of scripture, and stay in that word, and keep testing what they say. The thought here does not deny the real gift of prophecy which is primarily for others’ (in the church) strengthening, encouragement and comfort (1 Corinthians 14).
Going back to Jesus’s Sermon on the Plain, notice that teaching on judging others precedes the teaching on a tree and its fruit (the hyperlink above). We need to be careful that we’re actively judging ourselves, before we can begin to think we have the ability to help anyone else, or even see well enough to do so. If we excuse our own sin, and whatever evil is in our heart, then we will surely excuse the sin of others, just as long as they meet some agenda we think needs met.
But back to square one. We must keep the focus on our own hearts, bringing our sin to God in confession for forgiveness and cleansing through Jesus, as well as forgiving each other, praying for, and perhaps at times sharing a concern we might have for the well being of a brother or sister in the Lord. We’re all in this together, and God doesn’t change us in isolation from each other, but changes us both in fellowship or communion with God and with the family of God, as hard at times as that may be. And our first and foremost requirement in that is to deal with the sin in ourselves, so that we might be filled more and more with God’s goodness with the fruit of the Spirit in and through Jesus.