Matthew 7:15-20 — “Beware of false prophets [people who teach a works-based salvation message – “turn from your sins/follow the law to be saved”], who come to you in sheep’s clothing [their message sounds correct], but inwardly they are ravenous wolves [sending you to hell]. You will know them by their fruits [the fruit of their faith – what they believe saves a person]. Do men gather grapes [good fruit] from thornbushes [a worthless tree] or figs [good fruit] from thistles [a worthless tree]? Even so, every good tree bears good fruit, but a bad tree bears bad fruit. A good tree [a tree that produces the fruit of the gospel – salvation by faith in Christ alone] cannot bear bad fruit [a works-based salvation message], nor can a bad tree bear good fruit. Every tree that does not bear good fruit is cut down and thrown into the fire [unsaved people thrown into hell]. Therefore by their fruits [what they believe in] you will know them.
The above verses are always taken out of context by the false teachers – the very people they’re talking about – to teach a works-based salvation message. They turn the “fruit” into works, to say that anyone that doesn’t turn from their sins or do good deeds will be thrown into hell.
John 15:1-8 is where Jesus is explaining how He is the vine (like the root and trunk of a tree), believers are the branches that bear fruit, and God the Father is the vinedresser/gardener who cultivates the vine/tree.
Christ = Tree
Believers = Branches
Fruit = The message of the gospel (salvation by faith in Christ alone 1 Corinthians 15:1-4)
Vinedresser/Gardener = God the Father
The vinedresser/gardener wants His tree to make good fruit that is useful for Him and others. The good fruit believers produce for the vinedresser is the fruit of our faith (the fruit of our lips – what comes from our heart/mind – what we believe in for salvation – the gospel). This is fruit that others can pick from the tree of Christ, eat it and become truly nourished and it will give them eternal life.
The fruit of the good tree of Christ is not works. You can’t get nourished and saved by seeing my works – by seeing me turn from my sins or by seeing me do a good deed. So works can’t be the good fruit, and are not useful to the vinedresser or others. No one can eat my fruit of works and get nourished and saved.
Romans 11:16-24 tells us that when you eat that good fruit of the gospel (believe in the gospel), you are grafted into the tree of Christ as a branch and now produce the good fruit of faith that others can then pick from your branch and eat and become saved themselves. They are then grafted into the vine/tree of Christ as a branch and produce the fruit faith as well that others can eat of and be saved, and so on.