Not to state the obvious, but "knowing Christians by their fruit" does not mean that everyone who does something "nice" is a Christian. It does not mean that God is pleased with someone just because they give to the poor, attend church regularly, or sing in the choir. It doesn't mean that everyone you think is a good person is saved.
Fruit here refers to the natural attestations of the life one possesses within; it is the fruit of the Spirit. Apple trees naturally produce apples. Orange trees naturally produce oranges. They don't have to try to do this or work at it. In fact, they cannot help it. Even if they tried to produce some other fruit, they do not possess the genetic make-up to do it. Each must and does produce after its own kind.
So it is with the Spirit. To identify those who belong to Him, God has denoted the one thing which cannot be faked: life.
Prior to salvation, we were by "nature" children of God's wrath (Ephesians 2:3). After salvation we can become partakers of the divine "nature" of God (II Peter 1:4).
nature: Greek word physis; it means the nature of things, the force, laws, order of nature; birth, physical origin; the sum of innate properties and powers by which one person differs from others, distinctive native peculiarities, natural characteristicsWhen we speak of our "nature" we are talking about the very essence of who we are...and whose we are. Do we belong to the Lord or do we belong to Satan? How do we know? It is not about what we say or even what we do. It is not even who we think we are. It's about the nature we possess, and each nature has its own fruit.
"Now the works of the flesh are manifest, which are these; Adultery, fornication, uncleanness, lasciviousness, idolatry, witchcraft, hatred, variance, emulations, wrath, strife, seditions, heresies, envyings, murders, drunkenness, revellings, and such like: of the which I tell you before, as I have also told you in time past, that they which do such things shall not inherit the kingdom of God.
But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith, Meekness, temperance: against such there is no law." Galatians 5:19-23
"Then saith Jesus unto them, All ye shall be offended because of me this night: for it is written, I will smite the shepherd, and the sheep of the flock shall be scattered abroad. But after I am risen again, I will go before you into Galilee.
Peter answered and said unto him, Though all men shall be offended because of thee, yet will I never be offended.
Jesus said unto him, Verily I say unto thee, That this night, before the cock crow, thou shalt deny me thrice.
Peter said unto him, Though I should die with thee, yet will I not deny thee. Likewise also said all the disciples." Matthew 26:31-35
The first thing to notice about Peter is that he did not believe Jesus' words. He understood completely what Jesus was saying, but he did not believe Jesus. Even though Peter knew that Jesus was the Messiah - the Son of God - and that He had the "words of eternal life" (Matthew 16:16-17; John 6:68).
Because he did not believe Jesus, he made proclamations to contradict what Jesus said...twice! And Peter was not alone. All of the disciples disagreed with Jesus, in essence proclaiming that their own words were true and Jesus' words were false. Yet, we know that Jesus words were, of course, true.
"Now Peter sat without in the palace: and a damsel came unto him, saying, Thou also wast with Jesus of Galilee. But he denied before them all, saying, I know not what thou sayest.
And when he was gone out into the porch, another maid saw him, and said unto them that were there, This fellow was also with Jesus of Nazareth. And again he denied with an oath, I do not know the man.
And after a while came unto him they that stood by, and said to Peter, Surely thou also art one of them; for thy speech bewrayeth thee. Then began he to curse and to swear, saying, I know not the man. And immediately the cock crew.
And Peter remembered the word of Jesus, which said unto him, Before the cock crow, thou shalt deny me thrice. And he went out, and wept bitterly." Matthew 26:69-75
Peter not only denies knowing Jesus, he swears that he doesn't and goes so far as to speak profanities so as to convince others of his lies. Deep down - and in spite of what he declared earlier - Peter was still a liar, still selfish, still filled with wrath & profanity, etc. He did not have it in him to live the life he had sworn he would. Why not? Because Peter had not yet been converted. In an account in the book of Luke, it says:
"And the Lord said, Simon, Simon, behold, Satan hath desired to have you, that he may sift you as wheat: but I have prayed for thee, that thy faith fail not: and when thou art converted, strengthen thy brethren." Luke 22:31-32
Satan desired to "have" Peter. Yet, what Satan meant for evil, the Lord uses for Peter's good. The Lord let's Satan sift Peter so that he would learn that will power and religious posturing is not enough to live the life to which he was being called. The flesh will fail him every time and he should not be deceived by it. He needed something greater than, and outside of, himself to follow Christ. He needed the Holy Spirit.
"Then he answered and spake unto me, saying, This is the word of the LORD unto Zerubbabel, saying, Not by might, nor by power, but by my spirit, saith the LORD of hosts." Zechariah 4:6
The Holy Spirit is the power which changes us from one nature or type of life to another. Without the Holy Spirit, all you have is the old nature on display as it tries unsuccessfully to mimic the life of Christ within. From this text about Peter, we can see various truths about the old nature:
- Head knowledge is not belief. Knowing truth is not enough for the old nature to walk in it. You can acknowledge that Jesus is the Son of God and still not believe his words.
- Unbelief in Jesus' words will cause your own proclamations to be the opposite of what Jesus says. Your preaching will contradict the Scriptures.
- Such persons are prone to deceive themselves, stoically believing that they are some place spiritually where they are not.
- While the old nature may be able to blend into a religious environment for a time, it is all just emulations. No matter what they proclaim or believe to be true, there is nothing the old nature can do to actually live as a believer.
- When push comes to shove, the real fruit of that fallen nature will reveal itself.
How do you develop Godly fruit? Look back again to Galatians 5.
"And they that are Christ's have crucified the flesh with the affections and lusts." Galatians 5:24
The answer again is the cross. Without the cross, the old man is trying; with the cross, the old man is dying and God resurrects a new man who is empowered to live for Him by the Spirit.
It is not too late. If you know that you have been playing church - trying to suppress/ignore/forget the natural lusts of the old man within - all you have to do is turn your whole heart to the Lord. Forsake all to obtain Christ and offer back to Him the body & life He died to save (Luke 14:27; Romans 12:1).
"Repent ye therefore, and be converted, that your sins may be blotted out, when the times of refreshing shall come from the presence of the Lord." Acts 3:19