Jesus confirmed His teaching with miracles, signs and wonders. He told his Apostles to heal the sick, raise the dead and cast out demons, He gave them the authority, and they did.
Most of the church decided that the spiritual gifts - prophecy, miracles, healings etc. - were only for those Apostles. They were wrong, the gifts are actually given to all believers.
More Christians accept this and actually use the gifts in some ways in recent times. Note the start of big healing ministries in the late 1800s.
Yesterday I posted a comment including a list of names to look up. Those people describe healings and other miracles that God does now.
Hint - the more open minded people are about God's healings, the more there will be.