Faith has been dealt to every reborn man, but faith is not necessarily in use at all times amongst all reborn men.
Once I heard Keith Moore telling a story about when he was teaching at Rhema for Kenneth Hagin, and his car battery went dead and he was out waiting for a tow truck, when 2 of his students came by and saw him. And they asked him what he was doing and he replied. They then asked why he didn't just use his faith and speak to the car battery and command it to live in Jesus' name.
#1 he pointed out it was disrespectful for them to speak to their teacher like that, so curtly, BUT,
#2 he told them that thanks to something the Lord showed him not that long before this, he just didn't have it in his heart at the moment to believe God for that. And so he took the tow.
He elaborated saying that the Lord had told him if would get more selective about when he used his faith, he would be more effective when he did. Meaning, that when he had used, or thought he had used, his faith in the past and something didn't come to pass, he noticed it had a negative effect on his faith, so the Lord spoke that to him about making sure he really had it in his heart (faith) when he was going to release his faith on/for/in something.
I have noticed the same thing, and have been enacting this as well.
If someone has not built up their faith to believe for healing in a certain area, it doesn't mean they are less of a Christian or have less of the measure of faith (for God has already said in Romans that EVERY man has BEEN dealt THE measure of faith, meaning all reborn men got the same amount, and now it is up to us build it up by hearing the Word of God in whatever area (faith comes by hearing, and hearing by the Word of God (so reading the Word (aloud) and hearing faith preaching))), it just means they are not believing God in a particular area. It doesn't mean they are any less saved.
You are either saved or not saved, there are no degrees of being saved. There are types of faith however.
Jesus described certain degrees: no faith, little faith, faith and great faith (the last one being the Roman Centurion, who had greater faith than anyone born into the line of Israel ever to that point (even David, Elisha, Elijah, Abraham, etc) because He said of all the house of Israel).
And these were used to describe God's own people, including His own disciples.
Faith (with confidence) for healing will not come without revelation of God's Word concerning healing and the understanding of God's will (He has told us ALL (all Believers), His will is 100% healing 100% of the time - that's what He is offering and has already secured (back to Gal 3:13-14, 29, 2 Cor 1:20, Exodus 23:25-26, Isaiah 53:4-5, Matthew 8:16-17, Jer 30:17, Jer 1:12, Psalm 89:34...).
If God is the same yesterday, today and forever then healing is always His will, beyond the Scriptures I already gave above - how can God say He is the Lord Who heals you, but not heal you? That was given in the Old Covenant, and since we are now in a better covenant with better promises and terms (according to Hebrews), then EVERYTHING given in the Old Covenant would have to be included in the New Covenant PLUS more, or else the New Covenant would, by definition, be inferior to the old one.
Healing is yours, it is your bread, always; God has established His will and given it in His Word, and like dynamite, is only waiting for your faith to light the fuse.
Also remember that words can undo everything and anything you take by faith (Mark 11:24, you TAKE (the Greek word for receive there means literally, take) what things SO EVER YOU desire (not God, you) and that would include healing, so you have to take it, like taking possession of a good you buy in a store - you don't leave it there on the counter after you buy it and walk out).
If someone has not faith for healing or speaks against it, they should get medical attention, absolutely. And taking medicine does not mean you cannot have faith or build it up in this area. Start listening to faith preaching on faith, read the promises in the Word, declare them, TAKE them, like medicine
After all, Proverbs 4:20-22, the word for health there is "medicine", so God's Word is literally medicine to ALL your flesh. Powerful.
And lastly, as for being healed by His stripes already. You must see every sickness and disease and pain as an attack against you. You are not the sick trying to get a healing, you are the healed and Satan is trying to steal your health, putting junk on you, seeing if you'll agree with it and accept it. If he can get you to confess it, it'll stick, until you get rid of it with God's Word. (Proverbs 18:20-21 - words are containers for either life or death (and connected with Deut 30:19, also blessing and cursing)). Satan is the source of every sickness and every disease, God is never putting that trash on you, it's the Devil, and it's all an attack. Be proactive, lay down a blood-line of the Blood of Jesus all around your house, on every window and door and on every family member, declare Psalm 91 and 103 over your family and household. Life is in your mouth, and when you speak God's Word, in faith, the result will be good, very good.
And, being healed by His stripes already doesn't mean a Christian can never have a symptom of anything or whatever, in the same way being redeemed from poverty doesn't mean that a Christian cannot still be poverty-stricken, etc. It means it is a finished work and it's available, but it's not automatic.
When Jesus brought the net-breaking, boat-sinking load of fish for Peter did the fish jump in the boat? It was available. All Peter had to do was believe it and take it. Was Jairus' daughter automatically raised from the dead because Jesus COULD? No, it was available, but Jairus had to stay out of fear and stay in faith and take his little girl's miracle. Do farmer's crops jump into their barns? They are available, but the farmers have to go reap 'em.
Probably the best biblical example would be how AFTER coming into the Promised Land, flowing with milk and honey (good eating back then), only 5 of the 12 tribes, FIVE!, used their faith and took possession of what God said was theirs, especially Judah, the praising, faith-talking bunch.
The other 7 had to get a talking-to from Joshua about what in the world was the hold-up and why they, because of their unbelief (see Hebrews 3 and 4, plus Joshua 17-19), had yet to go what God had promised them. The key: IT WAS NOT AUTOMATIC even though it was God's will! That needs to be seen and understood, and we need to avoid their mistakes. 1 Corinthians says their mistakes were recorded so that we would not repeat them, and Hebrews 3 and 4 tells all about it, how to stay out of unbelief and through faith and patience inherit the promises of God.
Also consider that salvation, though God's will for all mankind, is not automatic, even though it's bought and paid for with Jesus' blood - you have to believe it and confess it and thereby take it. Healing is the same, prosperity is the same, victory is the same. Just don't let people or the Devil talk you out of it or try to outlast you.
