Bless the LORD, O my soul, and forget not all His benefits…who healeth all thy diseases (Ps 103:2-3) So does God really heal all diseases? I’ve known people who were healed of their disease. I’ve known people who died from their disease. Paul had some disease that God did not heal (2 Cor 12:79).
Timothy had stomach issues that God did not heal (1 Tim 5:23). So what gives if God can heal all diseases?
Yes, God can heal any and all diseases--He is LORD. Jesus proved His sovereignty over illness when He “healed all that were sick” (Mt 8:16). The key is the will of God. The leper told Jesus “If You will, You can heal me“.
Jesus replied “I will“, and the man was healed (Mt 8:2-4). If it’s His will to heal, then healing will come. Being the omniscient God, it’s His call for His purpose.
Disease is a product of this sin-fallen world.
But God allows disease and He will use it (or other things) to mature His people in their faith; to discipline His people from a sin; to prepare His people for deliverance into the healing of Heaven; and to draw unsaved people to Jesus.
A day is coming when disease won’t exist any more (Rev 21:4). Until then, God will allow disease for His purpose, and His purpose is always for our good and His glory, somehow, someway.