After the resurrection, Jesus Christ appeared to the apostles and commanded them to preach the word to every creature. As a result, signs followed. The apostles did exactly that and as a result a man who had been lame for his whole life received healing. Then, when the Word was spoken, around 5,000 men got born again. The new birth is the ultimate healing. The Word of God is healing, and since God energizes His Word as we believe it, we can do the same signs and wonders that Jesus Christ did. We have Christ in us, so, as his representatives, we have the same directives and the ability he had.