Baker Encyclopedia of the Bible says this about the word Defile:
“To make ethically or ritually unclean. “
The book of Leviticus gives a much deeper explanation about what God says about clean and unclean. Its also pointed out in Psalms 24:3-4 where it says “Who shall ascend the hill of the Lord? And who shall stand in his holy place? He who has clean hands and a pure heart, who does not lift up his soul to what is false, and does not swear deceitfully.” A persons state of whether or not they are clean does not just depend upon their external actions, but also involves there internal relationship with God. This is where complete and total dependence on God and His provision is needed. The sinner has no ability at all to satisfy the moral demands of a holy God.
If we look at the Mosaic law which was given to Moses by God for how the Israelite's were to live you will see a few things:
1. Some foods were not to be eaten. Various laws concerning animals make a “distinction between the unclean and the clean and between the living creature that may be eaten and the living creature that may not be eaten” (Lv 11:46, 47). Permitted food was what was acceptable to God (see also Dt 14:3–21; Acts 15:28, 29).
2. Diseases, especially leprosy, produced an unclean state (Lv 13, 14). The story of Naaman refers to leprous defilement (2 Kgs 5:1–14). The Gospels refer often to lepers (e.g., Mt 8:1–4; 10:8; 11:5; Lk 4:27). Many swellings, sores, and rashes were included under that heading, including Hansen’s disease (modern leprosy). The defilement of disease included all things touched by a diseased person (Lv 14:33–57).
3. Dead bodies, or even parts of them such as bone, caused uncleanness (Nm 19:16). Persons who touched a dead body were unclean for a month, and only after that period could they celebrate their own Passover if they had missed it (Nm 9:6–11). The high priest could not even bury his own parents because of his special ritual responsibilities (Lv 21:10, 11; cf. Nm 6:7; Hg 2:13; Mt 23:27).
4. Idolatry was the greatest source of spiritual defilement. The entire nation of Israel was defiled because of it (Ps 106:38; Is 30:22; Ez 36:25), as were the Gentiles (Jer 43:12). Consequently, contact with Gentiles was thought to produce defilement. The gospel’s universal appeal confronted that conviction (e.g., Jn 4:9; Acts 10:28; cf. Gal 2:11–14). Closely related to the defilement of idolatry was the defilement caused by unclean spirits (Zec 13:2; cf. Mt 10:1; Mk 1:23–27).
Other relating passages to defilement are:
Le 15:16–19, Le 15:24–25, Le 17:15–16, Le 20:3, Le 22:4–8, Nu 19:7–16, Is 59:3, Je 3:1, Eze 44:25–26, Mt 15:18, Mk 7:2–5, Jn 18:28, Ac 21:28, Heb 12:15
There was a time that the temple was defiled by idol worship and in order for God to accept once again the scarfices by the high preist the temple had to be cleansed. (2 Chr 29:15–19); Nehemiah had to cleanse the rooms in which Tobiah had been (Neh 13:9).
The New Testament also speaks to the temple being defiled by those who were money changers in the temple court. Jesus cleared out the temple by making a wipe from what materials He could find and wiped the money changers and flipped over tables saying “It is written, My house will be called a house of prayer. But you are making it a den of thieves!” Matt:21:13
The religious leaders at that time were unclean and making others who needed to buy sacrifices defile themselves. Jesus continually had to rebuke those leaders daily.
Has this changed at all in the last 2000 years? No!
Today we do the same. How?
Here are just a few examples.
We lie (this also includes white lies). Though we make excuses for why we do it like, to spare someone's feelings, its still a lie. We also cheat. Cheating has a wide rage of possibilities. The person you are in a relationship with, or on taxes even when you play a game with someone. Cheating is pretty much anything you can do that benefits you. Stealing is a part of defiling yourself and that can mean the smallest of things because taking the smallest of things that you know doesn’t belong to you is still stealing. Christ on many occasions addressed people's heart. Since most people when asked if they consider themselves to be a good person they answer yes. The problem is however they are using standards they have created which make them look like a saint not a sinner. They fail to see that God's standards are much higher. The New Testament even has those who said they obey and follow the commandments given to Moses by God yet the Lord Jesus took it a step further by saying that even if you look with lust it is the same as committing the sin of adultery, or even if you say to someone “I hate you” (Racca) you have committed murder.
Defilement also can be the result of making oneself or someone else unclean in God’s sight.
There are two very distinct differences for defilement are outward & spiritual.
Outward defilement is physical and that comes from contact with someone
Lev 20:25 See also Lev 7:19-21; 11:41-45; 21:1-4; 22:4-5; Nu 5:1-3; 6:9,12; Eze 4:9-15; 44:25; Da 1:8; Hag 2:10-14; Mal 1:7
Sin however produces inner, spiritual defilement.
Eze 14:11 See also Lev 19:31; Ps 106:34-39; Jer 2:23; La 4:14; Eze 20:1-44; 22:1-4; 23:28-30; 37:23
Paul reminds us in 1 Co 6:19–20 “Don’t you know that your body is a sanctuary of the Holy Spirit who is in you, whom you have from God? You are not your own, for you were bought at a price. Therefore glorify God in your body.” In the entire text Jesus was telling those who wanted to follow Him that our bodies are apart of Christ. They no longer belong to us. We have to stop feeding our bodies with the things that defile our bodies and begin to feed our spiritual bodies with the things which are pure, holy, trustworthy, noble.
When we have come to the knowledge of Jesus Christ and what He did for us on the cross it is because the Holy Spirit of God showed us we were in need of a Savior. No one comes to this knowledge by there own understanding because the world loves darkness and are not interested in the things of God.
In our new life as a Christian we will receive the Holy Spirit., and since this Holy Spirit lives in us and operates through us we must make sure we have a clean home. This doesn’t mean you will do everything just right and perfect but it is a process in which we grow as believers.
Therefore, if anyone is united with the Messiah, he is a new creation—the old has passed; look, what has come is fresh and new! 2nd Co 5:17
Ehp 4:24 and put on the new man (in accordance with God), who is created in righteousness and holiness from the truth.
Col 3:10 and have put on the new man that is being renewed in knowledge according to the image of the one who created him
Ro 6:4 | Therefore we have been buried with him through baptism into death, in order that just as Christ was raised from the dead through the glory of the Father, so also we may live a new way of life.
Ro 8:29 | because those whom he foreknew, he also predestined to be conformed to the image of his Son, so that he should be the firstborn among many brothers.
Ro 12:2 | And do not be conformed to this age, but be transformed by the renewal of your mind, so that you may approve what is the good and well-pleasing and perfect will of God.
If we have confessed to being a believer and follower of Jesus we must be able to show that by how we live. This is seen in our actions, our speech, our very behavior. If someone you know claims to be a Christian yet the actions are anything but that, chances are they are not Christians, or they haven’t repented those issues which are defiling their bodies. Think about speech? Would you be able to say that a Christian who curses all sorts of vile words is a Christian? Our life before Christ may have been that with curse words yet now our life is transformed and we no longer do those things. What about someone who tells crude jokes. Jokes can be funny and of course there is much humor in the bible but shouldn't a child of God put off that old habit and take on the new life found in Christ. Its time we deal with behavior and we must be bury the old life. Think to a funeral you’ve attended. Usually in that service you may see pictures of that person growing up, memories they made, sometimes a poem or a song is sung and then after the service they are buried. We don’t come a week, a month, or a year later and dig them up. That would be foolish and the stench would be unbearable. The same thing can be said of the person who came to the saving knowledge of Jesus Christ. They became a new creature, after growing more in Christ and understanding His ways, they decide it’s good to be baptized. We know that baptism is a visual of the old man being buried and the new man rising up out of the water.
There is a constant battle with the flesh and our spirit. The old nature wants to fight for selfish rights. It wants what it wants not what God wants for us. Remember that a Christian is also crucified with Christ (Gal 2:20). We “no longer live but it is now Christ who lives in us.” At the same time it’s also Luke 9:23 says that we are to “pick up our cross daily and follow Him.” When we come to this realization and start living for Him then we will no longer be defiling our temple physically or spiritually.