To defile (degrade, violate) something is an act of great disrespect toward God, a person, a community, or a nation. Defilement is normally associated with sexual impurity committed against a person; as horrible as this is, the most serious implication of sin's contamination is seen as an offence against God's standards and hinders a relationship with God (Ps 51:4; Isa 59:1,2). This is why Jesus came to earth and died in our place to make possible a return to restoration that culminates in heaven.
Sin brings defilement
(Prov 4:23; Mk 7:21-23; 2 Cor 10:5; Heb 12:15). “If anyone defiles God’s temple, God will destroy him; for God’s temple is sacred, and you are that temple” (1 Cor 3:17, 6:18-20). This is a solemn responsiblity to ensure our body, in which the Holy Spirit resides is continually cleansed of the sin that subtly infitrates, otherwise it gives a foothold for Satan to defeat us (Eph 4:27). Jesus said, not just wrong actions are sinful but so are wrong thoughts (Mt 5:27,28).
"Daniel resolved that he would not defile himself..." taking a deliberate stand against external sources of contamination (Dan 1:8). Godly values must rule all aspects of our lives. Another major source is idolatry which is cherishing something more than Christ (Ex 20:3; Mk 12:30). .
Regularly ‘spring-clean’ your life to replace the pollution with purity
is just and right, he will surely live; he will not die” (Ezek 18:21). Note the personal responsibility, to actively “Put to death, whatever belongs to your earthly nature, sexual immorality, impurity…Cleanse and purify your hearts” (Col 3:5-10; Jas 4:8). Thank God for the blood of Christ for, “If we confess our sin, He is faithful and just and will forgive us our sins and purify us from all unrighteousness” (1 Jn 1:9). It is only the blood of Jesus Christ that is powerful enough to cleanse our hearts and make us fit to commune with God (1 Jn 1:7). We are not to continue in sin but walk in newness of life in Christ, not returning to that which once held us (Rom 6:1,4; Gal 5:1; 2 Pet 2:22). Thus as we walk in the Spirit, defilement will not define us (1 Cor 6:9,10; Gal 5:16,19-21; 1 Jn 3:6-10).
In the OT a defiled person could not enter the sanctuary of the Lord, and for us today partaking of communion is not advisable while there is unconfessed sin or issues we have not resolved (Num 19:13,20; Mt 5:23,24; 1 Cor 11:27,29).