What are the things that defile the temple (body)?
In 1 Corinthians 3:16 and 6:19 the Holy Spirit tells us that each individual person who trusts Jesus Christ to forgive his or her sins is a temple of God and the Holy Spirit dwells within us. If God the Holy Spirit dwells within us, then we are a temple of God – a fleshly one. The body of a Christian is a temple of God the Holy Spirit.
Do you not know that you are a temple of God and that the Spirit of God dwells in you? (NASB) 1 Corinthians 3:16
Or do you not know that your body is a temple of the Holy Spirit who is in you, whom you have from God, and that you are not your own? (NASB) 1 Corinthians 6:19
2 Corinthians 7:1 says that we can defile our bodies and thus the temple of God by sinning.
Therefore, having these promises, beloved, let us cleanse ourselves from all defilement of flesh and spirit, perfecting holiness in the fear of God. (NASB) 2 Corinthians 7:1
In order to understand this passage, we must read the verses that come before and after the verse. The verses, starting with 2 Corinthians 6:18 warn us to flee immorality or sexual sins. The verses that follow 2 Corinthians 7:1 also discuss sexual purity. Now notice that 2 Corinthians 7:1 tells us to be holy. How do we defile ourselves? When we commit any type of sexual sin. In reality, we defile ourselves whenever we sin, especially when we commit sexual sin.
God warns us in 1 Corinthians 6:18-20 that sexual sin is against one’s own body. All other sins are outside the body. That is, the temple of God. Other sins are damaging as well. If we sin, we need to confess our sin to the Lord and He will forgive. That is His promise.
If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness. (NASB) 1 John 1:9