Trying to find a topic that we can amicably disagree on, hopefully this is it. Scripture seems to support and promote that God heals us from all sickness and conditions.
Psalm 103:3 He who forgives all your iniquities and heals all your diseases,
Matthew 4:23 Jesus went throughout Galilee, teaching in their synagogues, preaching the gospel of the kingdom, and healing every disease and sickness among the people.
But most all of us have experienced times when we ask for and seek healing and it does not come. Now, a caveat to this discussion is I'm asking you not to use "It's God's Will" as a response to this. Is there scriptural support for the idea that we cannot be healed of some conditions?
Like, are there limits to what we can and cannot be healed of?
What is our response to people who genuinely ask for healing but do not receive it?
Psalms 103 is a prophecy of life for Israel under their promised kingdom on Earth, during the millennial reign of Christ.
Salvation for them is tied to the promised kingdom of God on Earth, is something they expect in the future (Hebrews 8:8-12, Acts 3:19-21, 1 Peter 1:9).
So Psalms 103, especially the lovely verses from 1-5, specifically tells you what they expect to receive when that kingdom begins (vs 19), which in vs 3, includes both forgiveness of their sins, and physical healing from their diseases.
It is inline with Isaiah 33:24 said as a cross reference of life under that kingdom
And the inhabitant shall not say, I am sick: the people that dwell therein shall be forgiven their iniquity.
As for Matthew 4:23,
Jesus was sent to save Israel in his first coming (Romans 15:8, Matthew 1:21, Matthew 15:24, Luke 1:68-75)
Like how Moses was recognized by Israel thru signs (Exodus 4:29-31), Israel will likewise recognize Jesus by the signs that he will perform. (Deuteronomy 18:15, Luke 7:20-22, Acts 3:22-23, John 11:45-48).
Israel's correct response to those signs is to believe that he is THAT promised Messiah (Deuteronomy 34:10-12, John 6:28-29, John 20:30-31, John 10:37-38).
So us gentiles in the Body of Christ should not directly look at Jesus first coming to claim those same healings that is a central feature of the gospel of the kingdom (Matthew 10:5-8).
But we can certainly commit to Christ all our requests, including healing from our physical diseases, since Paul our apostle instructed us to (Philippians 4:6).
God can certainly heal today still, and he has.
The main difference is that Paul did not teach us that healing is promised to us in the Body of Christ. the only promise is that God will send to us his peace, that passes all understanding (Philippians 4:7).
Interestingly, the last verse was emphasized by Bill Johnson in the sermon he preached immediately after his wife's passing from cancer. That is a good answer and example to your last question.