A healthy tree bears good fruit, but a poor tree bears bad fruit. Matthew 7:17
Jesus taught about false prophets who looked like sheep on the outside, but on the inside they were really like wild wolves. This was their hypocrisy, but we would then know them by what they do.
It is like by looking at a tree to know its nature and productivity by its fruit. For Jesus said a healthy tree bears good fruit and a poor tree bears bad fruit. Thorn bushes do not bear grapes and we can only get grapes from a vine-yard.
This also applies to a family, a society, a school and even to a church. The parents of a family who are unkind could hardly raise up children who are loving. A society whose leaders are irresponsible could hardly have a good committee. Teachers who do not teach with love can never help poor students to improve in their studies whereas if the head of a church does not talk about the spiritually of Christianity would only have reluctant parishioners.
As says in Galatians; the Spirit produces love, joy, peace, patience, kindness, goodness, faithfulness, humility and self-control. The Spirit is the one who gives us life. And those who belong to Christ Jesus have put to death their human nature with all its passions and desires.
Our lives must be controlled by the Spirit by bearing fruit of the Holy Spirit as to be said as healthy tree bearing good fruit; those of the Spirit. A good person is like a healthy tree which bears good fruit, the reality of its life.
As the flower is before the fruit, so is faith before good works.