God's temple on earth, Paul wrote, is the church.  God used to dwell in the most holy place of the Old Testament tabernacle, and later the temple, but God now lives within all who worship Jesus Christ as Lord and Saviour.  So, He does not reside only in one geographical location or physical building; wherever His people are found, God's Spirit is there too.

False teachers threatened to break up the church in Corinth as believers were confused by preachers pulling them away from the gospel of Jesus.  So Paul reminded them that those leaders were not just altering a human organisation but destroying the dwelling-place of God.  The church, imperfect though it is (and always will be until Jesus returns), is so precious to God that His anger is fierce against those who wreck it by distorting the truth upon which it is built (1 Corinthians 3:11).

It is true that, individually, Christ lives in our hearts by faith because the Holy Spirit enters every person who trusts in Jesus for their salvation. So each believer's body is a temple of the Holy Spirit (1 Corinthians 6:19).  But it is also true that where two, three or more believers are together, Christ is in them corporately (Matthew 18:20).  Some mistakenly think that God only lives in consecrated buildings.  Where He does, it is because His people are there and He is in them (John 14:23).  The preciousness of the church to God cannot be underestimated.  We, together, are as dear to Him as His family; which is what we are (Isaiah 40:11).

Paul was giving a straight message: do not break up or divert the focus of God's church through false doctrine or personal agendas.  God watches over His people and is passionate that they speak the truth about Jesus.  The church is God's masterpiece and He will personally deal with those who lead people away from Jesus.  It is a solemn warning to leaders and those who support them.  It is also a wonderful comfort for all who hold to the undiluted gospel: they and their Christian brothers and sisters are immensely precious to Him.