"Whosoever is born of God doth not commit sin; for his seed remaineth in him: and he cannot sin, because he is born of God." 1 John 3:9 King James Version
Whenever there seems to be a contradiction in the Bible that means we need to study the issue at a deeper level to find out what the Bible is really saying. We cannot take a scripture out of context in such situations and build a doctrine out of it when that doctrine contradicts other scripture. We must look at the chapter, the book from which it was written, and the Bible as a whole, to get the correct meaning. Yes, this sometimes means we may have to take a look at the original language to get the correct interpretation.
1 John is a letter written to Christians. This is evident from many of the verses within the letter itself such as 1 John 1:4 "And these things write we unto you, that your joy may be full." This not a statement that would have been made if he were writing to the unsaved. It was a letter written to the churches at that time to encourage them. This same author that wrote 1 John 3:9 wrote 1 John 1:8-10 which appears on the surface to contradict 1 John 3:9. By the way this is only one example in the Bible that makes reference that Christians do battle sin. They are too numerous for me to address them all.
1 John 1:8-10. King James Version says "If we say that we have no sin, we deceive ourselves, and the truth is not in us. If we confess our sins, he is faithful and just to forgive us our sins, and to cleanse us from all unrighteousness. If we say that we have not sinned, we make him a liar, and his word is not in us. This is written to saved, born of the Spirit Christians!
We will find when we do an in depth study of this issue that there are no contradictions.
"There is no contradiction. What is happening is that John is saying that the one who is born again does not habitually abide in sin. He may fall into it, but he does not practice it as a lifestyle. The nuances of the Greek language are not carried over to the English, but when we understand what is happening we then see there is no problem.
Finally, any Christian who would say that he does not sin anymore fails to agree with 1 John 1:8 which says, "If we say that we have no sin, we are deceiving ourselves, and the truth is not in us." He would then be self-deceived." End quote.
A person who is saved is a new creature in Christ and will not want to sin. "Therefore if any man be in Christ, he is a new creature: old things are passed away; behold, all things are become new." 2 Corinthians 5:17 KJV
A person who is born of the Spirit will want to follow and obey Jesus and seek to please Him in every way. A saved person will hate his sin and seek deliverance from any bondage to sin. He will not want to keep in that sin. We come to God just as we are in all of our filth of sin. We grow in Christ. The more mature we are in Christ the less we sin. This can be seen as we read on in this book. A true Christian does not willfully practice sin, but he is not perfect either. A true Christian will do battle against sin in his life.
Moving on in the book of 1 John to chapter two we can see further evidence that the author is writing to Christians.
1 John 2:21 is another proof that this whole letter was written to the saved. " I have not written unto you because ye know not the truth, but because ye know it, and that no lie is of the truth." Also, 1 john 2:14 proves this letter is to saved Christians. "I have written unto you, fathers, because ye have known him that is from the beginning. I have written unto you, young men, because ye are strong, and the word of God abideth in you, and ye have overcome the wicked one." A reading of the whole book should make it clear to you that this is a letter written to Christians to encourage them. I'm sure I don't have to point out every verse to prove that to you. Some of the encouragement is to keep themselves from sin.
Also, we can see that the author is addressing the different levels of maturity in Christians. In chapter two we see the author addresses some as "little children". He addresses others as "young men" and still others as "fathers". It is the "little children" that he is most concerned about when it comes to sin. These are the babes in Christ. It appears that the "little children" or the less mature in Christ have yet the most sin to overcome.