But Jesus beheld them, and said unto them, With men this is impossible; but with God all things are possible. Matthew 19:26
The key word here is sovereign in that God knows all, sees all and is aware of all. There are times that healing and deliverance does not come. Sometimes it is due to our own disobedience to God and His word but there are also times when God's will supersedes our will and desires.
And many lepers were in Israel in the time of Eliseus the prophet; and none of them was cleansed, saving Naaman the Syrian. Luke 4:27
We are not told why this was so.
And he took the cup, and gave thanks, and gave it to them, saying, Drink ye all of it; For this is my blood of the new testament, which is shed for many for the remission of sins. But I say unto you, I will not drink henceforth of this fruit of the vine, until that day when I drink it new with you in my Father's kingdom. Matthew 26:27-29
We can fail to discern the Body of Christ in three ways:
A time to be born, and a time to die; a time to plant, and a time to pluck up that which is planted; Ecclesiastes 3:2
And as it is appointed unto men once to die, but after this the judgment: Hebrews 9:27
Even the great prophet Elisha, who did many miracles of healing and deliverance, became "sick with the sickness whereof he would die"
Now Elisha was fallen sick of his sickness whereof he died. . . II Kings 13:14