1 Corinthians 6:15:

Know ye not that your bodies are the members of Christ? shall I then take the members of Christ, and make them the members of an harlot? God forbid.

Notes on 1 Corinthians 6:15:

God says that your physical body is a member of Christ!  We are used to thinking of ourselves as members of Christ spiritually, but God goes beyond that and says that your body belongs to Christ as well!

Can Jesus Christ, who healed the sick everywhere He went, want anything that belongs to Him to be sick?  No.  If He healed those who were not born again in His ministry, how much more should He heal a body that is a member of Himself?

See also:

Your Body Is God’s Property
Who You Are and What You Have
Objection: Our Bodies Are Not Yet Redeemed, So We Are Still Subject to Sickness
Objection: Teaching Grace Gives People a License to Sin