"And he called the multitude and said unto them, Hear and understand: Not that which goeth into the mouth defileth a man; but that which cometh out of the mouth defileth a man.  
Matthew 15:10-11

I have heard many use this scripture to justify smoking, drinking, and the such like, things that are obviously harmful to the physical body.  And it seems, without really understanding the mind of Christ, that He was not condemning such things.  But let's take a deeper look into this scripture. 

In this particular scripture, Jesus used the reference "a man".  Why?  Because Jesus was speaking about the "spirit" that man manifests, not about the body itself.  As we read verse 18, Jesus makes it clear that "those things which proceed out of the mouth cometh from the heart; and they defile the man."  His continues to speak of evil thoughts, murders, adulteries, fornications, etc..., as those things which come from the inner man and not from the body.  They come from the spirit of the man. 

"Know ye not that ye are the temple of God, and that the Spirit of God dwelleth in you?  If any man defile the temple of God, him shall God destroy; for the temple of God is holy, whih temple ye are." 
1 Corinthians 3:16-17

The word "defile" means to become unclean, to pollute, or to become impure; to render unholy or profane; to violate the chastity, the virginity, or the purity of something.  It is the exact opposite of "consecrate", which means to sanctify, dedicate, to make holy; to prepare oneself to fulfill spiritual purpose". 

Paul was very clear in his explanation about this.  Our bodies are the temples where God's Spirit resides, and we are not to defile them.  He is, in these passages, speaking about those things that we put "into" our bodies, not that which comes out of them.  He is talking about our fleshly temples, not that which defiles by actions or attitudes.  He's talking about that which is defiled by intake, not output. 

These scriptures have been the source of much contention, for carnal minded teachers who have compromised the word of God, have given license to things that God has not licensed.  God will destroy every one of us who defiles His temple, for He wants us to keep His temple clean.  Don't believe me?  Read this very carefully.

"I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service"
Romans 12:1

Notice that Paul said bodies and not spirits.  He commanded the people to present their bodies holy and acceptable unto God, meaning that he was forbidding the defilement to which many of us engage ourselves.  We should take much better care of the temple that God has given us, and that includes not eating pork or other foods that are harmful to us, smoking cigarettes, drinking alcoholic beverages, or abusing other substances that are harmful to our bodies. 

Now the commandment of Christ that we defile not ourselves with those things we speak or in actions from our inner man is just as important, if not more so, than Paul's admonition.  Why?  Because there will be a day when God will judge every one of us according to content and intent of our hearts.  The word itself is a discerner of the thoughts and intents of our hearts, and He shall leave nothing unrevealed. 

"But Daniel purposed in his heart that he would not defile himself with the portion of the king's meat, nor with the wine which he drank"  
Daniel 1:8

Jesus rebuked the scribes and Pharisees on several occasions because they placed more emphasis on making sure they "looked" clean on the "outside" while their hearts were filled with contention, wrath, hypocrisy, and deceit.  He called them "false prophets" who looked like sheep on the outside, but their inside was like "ravening wolves".  These points emphasize our need to be born again, not just outwardly clean, but inwardly also. 

God has always and always will hate things that defile, whether it's by things we put into our bodies or by the things that come out of our mouths.  We are called to lights to our generation, cities who are set upon a hill for others to follow.  Our lights should shine brightly so that we can lead others to holiness, something we cannot do if we lack the power to keep our flesh under subjection.  We should not yield ourselves to obey it's lusts, but we should maintain power and victory over it at all times.  Amen. 

"What? Know ye not that your body is the temple of the Holy Ghost which is in you, which ye have of God, and ye are not your own?  For ye are bought with a price: therefore glorify God in your body, and in your spirit, which are God's" 
1 Corinthians 6:19-20