Possible causes of illness or infirmity:
The Bible teaches that original sin introduced a fallen nature to our world and with it, our bodies. (See Genesis 2:16-17) Illness or infirmity can also be attributed to poor health and lifestyle choices, because God gave us free will to make choices. A third factor to consider is what the Bible says about the enemy of our souls, that he "comes only to steal and kill and destroy." In contrast, Jesus promises: "I have come that they may have life, and have it to the full." (John 10:10 NIV) Health problems can steal our energy, strain our relationships and finances, and rob us of the ability to fully release our Godly purposes on Earth. However, we know that God’s desire is to see us live life to the fullest, through Christ Jesus.
Jesus is the Author and Finisher of our faith. (see Hebrews 12:2) We must trust that He knows what is best for us. Repeatedly, the Bible reveals the true character of God- that He is Good. “For the LORD is good. His loyal love endures, and he is faithful through all generations.” (Psalm 100:5 NET Bible) When it comes to illness and infirmity, we know that God is a loving Father Who always has our highest and best outcome in mind. Matthew 7:11 states: “Even though you're evil, you know how to give good gifts to your children. So how much more will your Father in heaven give good things to those who ask him?” (GWT)
So even though it grieves God to see humans suffer, because He is a good God, full of redemption, He will bring positive fruit out of our experiences as we yield to Him. “You, Lord, are forgiving and good, abounding in love to all who call to you.” (Psalm 86:5 NIV) Health trials can produce the treasured characteristics of God in our life- such as patience, long suffering, peace, kindness, humility, and so forth. Ideally, a yielded vessel will draw closer to know Him more intimately. "For our present troubles are small and won't last very long. Yet they produce for us a glory that vastly outweighs them and will last forever!" (2 Cor. 4:17 NLT)