Our second reason for not doing prayers for healing in evangelism is: "There is a greater need":
While an unbeliever having a physical ailment or lower back pain may be inconvenient to him, it’s definitely not his greatest need. For many have gone to hell with perfectly shaped backs or healthy bodies.
The unbeliever’s greatest need is that of salvation. For Jesus said “What does it profit a man if he gains the whole world and forfeits his own soul?” (Mark 8:36)
By focusing on someone’s physical predicament at the expense of his eternal predicament, reaffirms in the unbeliever’s mind that what he needs most is for his body to become better.
Instead we want the unbeliever to know that at the present time God’s wrath abides upon him because of his sin, and that at any time his heart could stop beating and he would be swept into hell for eternity. This is serious, and this is what the unbeliever needs to see is his greatest need.
So let’s warn the unbeliever about this and make our focus the gospel which is the solution of his greatest need, and not peripheral issues.