It's promised to all believers in Jesus Christ. Either you believe it or you don't.
I do agree that we are all seriously in doubt these days.
What does scripture say about doubting?
James 1:5-8
If any of you lacks wisdom, let him ask God, who gives generously to all without reproach, and it will be given him. But let him ask in faith, with no doubting, for the one who doubts is like a wave of the sea that is driven and tossed by the wind. For that person must not suppose that he will receive anything from the Lord; he is a double-minded man, unstable in all his ways.
I did not come to Christ through anyone or any church. I believed when the Lord touched my heart and spoke to me. I believed in faith. Even though people will try to get me to doubt the truth of the matter.
I think one of the problems of why we don't see healings and miracles today is because we put too much emphasis on it being "us" that does the healing, instead of truly trusting that God is doing it. We may be instruments that He uses to work in this world but we are not the one's that get the glory for it.