Some faith healers teach it’s always God’s will to heal deformity, sickness and disease immediately, that if we’re suffering physically in any way it’s due to sin and/or our lack of faith in God: in other words, our own fault.
Though it’s true that sin can cause physical weakness, disease and sickness (1Co_11:30), Scripture never presumes sin is the sole cause, or even a typical one. Nor does it teach that being sick for a season is necessarily our fault; it does not teach that it’s always God’s will to heal us immediately. For the innocent, presuming sin is the reason for affliction, or even a lack of faith, adds insult to injury. (Jn 9:3)
Case in point is Epaphras, a dear man of God who became sick while serving Christ. (Php 2:30) He didn’t have authority to heal himself immediately, nor did Paul. His healing came at the last minute, and it was undeserved: God had mercy on him. (Php 2:30) If his state had anything to do with a lack of faith, Paul wouldn’t have tolerated it.
Trophimus, who ministered with Paul, became so sick Paul had to leave him behind. (2Ti 4:20) And Timothy had such physical problems Paul suggested a dietary change. (1Ti 5:23) Again, if a lack of faith were the sole cause of seasons of weakness and sickness, these texts would not be written as they are.
At times, Paul himself took pleasure in being afflicted with various infirmities as a way to reveal the sufficiency of God’s grace in his life (2Co 12:10); he didn’t presume it was always God’s will to heal immediately.
Granted, at times, God may be willing to heal instantly and miraculously, and we might, in fact, forego healing due to our lack of faith (Mt 17:19-20): anything we ask in faith, we receive. (Mt 21:22) We often suffer because we don’t pray, and even when we do pray it’s selfish, and so in vain. (Ja 4:2-3)
But God is no man’s servant; He isn’t this giant, cosmic vending machine dolling out gifts to those who have the right feelings or speak the right words. There’s nothing we can do to manipulate Him, and presuming we know His will in a situation can lead to tremendous pain and frustration. His ways are often mysterious, and His will in any given situation is not, in my experience, obvious. I think the key is in understanding what it means to ask in faith, and how this works.
To pray in faith is to pray knowing the will of God (1Jn 5:14) for the glory of God. (Php 1:21) Faith isn’t about trying to make ourselves believe something, it’s about walking so closely with God that we sense what He’s doing to glorify Himself. (Jn 5:20) Thinking faith is something else is misguided.
Trying to manipulate the physical world through our will or technique is the essence of witchcraft. The human soul in itself is exceedingly powerful; we must carefully distinguish between godly faith and presumption. The slightest twist of God’s truths can make them poisonous; if we aren’t careful we may, like faith healers often do, use them like knives to wound the innocent. (Pr 12:18)