I can only answer the first part of your inquiry.
"Why God doesn't intervene when we want Him to." This answer is quoted from
Bible Questions Answered
Assumption 1: God is bound to say "yes" to any prayer offered in faith.
Jesus said, "I am going to the Father. And I will do whatever you ask in my name, so that the Son may bring glory to the Father. You may ask me for anything in my name, and I will do it" (John 14:12-14). Some have tried to interpret this passage as Jesus agreeing to whatever we ask. But this is misreading Jesus’ intent. Notice, first, that Jesus is speaking to His apostles, and the promise is for them. After Jesus’ ascension, the apostles were given power to perform miracles as they spread the gospel (Acts 5:12). Second, Jesus twice uses the phrase "in My name." This indicates the basis for the apostles’ prayers, but it also implies that whatever they prayed for should be consonant with Jesus’ will. A selfish prayer, for example, or one motivated by greed, cannot be said to be prayed in Jesus’ name.
We pray in faith, but faith means that we trust God. We trust Him to do what is best and to know what is best. When we consider all the Bible’s teaching on prayer (not just the promise given to the apostles), we learn that God may exercise His power in response to our prayer, or He may surprise us with a different course of action. In His wisdom He always does what is best (Romans 8:28).
Assumption 2: God’s future healing (at the resurrection) cannot compensate for earthly suffering.
The truth is, "our present sufferings are not worth comparing with the glory that will be revealed in us" (Romans 8:18). The believer has God’s promise of future wholeness, and faith is "being sure of what we hope for and certain of what we do not see" (Hebrews 11:4). Jesus said, "It is better for you to enter life maimed or crippled than to have two hands or two feet and be thrown into eternal fire" (Matthew 18:8). His words confirm the relative unimportance of our physical condition in this world, as compared to our eternal state. To enter life maimed (and then to be made whole) is infinitely better than to enter hell whole (to suffer for eternity).
Assumption 3: God’s plan is subject to man’s approval.
One of the contentions is that God just isn’t "fair". Yet, Scripture is clear that God is perfectly just (Psalm 11:7; 2 Thessalonians 1:5-6) and in His sovereignty answers to no one (Romans 9:20-21). A believer has faith in God’s goodness, even when circumstances make it difficult and reason seems to falter.
Assumption 4: God does not exist.
Her arguments start with the assumption that God does not exist and then proceed to buttress their idea as best they can. For them, "religion is a myth" is a foregone conclusion, presented as a logical deduction but which is, in reality, foundational to the argument.
An answer, in short, would be something like this: "God can heal us and will heal every one of us who trusts Christ as Savior. The healing will come, not as the result of our demanding it now, but in God’s own time, possibly in this life, but definitely in heaven. Until that time, we walk by faith, trusting the God who redeems us in Christ and promises the resurrection of the body."