I have never encountered any evidence that would make me presume else wise
And so you take all accounts of miracles when someone tells you of them as false, as you require your own first person experience to admit not even the actuality of something, but even the potentiality of it?
Christians don't become Christians because they see miracles happen. They see miracles happen because they are Christians.
In fact, Craig Keener has pointed out that miracles are the most common among the mission field, areas with limited prior exposure to Christianity.
Sources like the China Christian Council (see 14:20) shows a large percent of Christian converts (up to 90 pct in rural areas) in China cite a healed illness as a reason for conversion*to Christianity*. So it is clear that God, among other means, provides clear testimony to the gospel to people who have never been exposed to the faith before through miraculous healing.
A few more points from 17:00: Similarly, in an area in Suriname, a non-Christian man had his arm (which had been paralyzed all his life) instantly shot up, and that led to a "people movement" in Nickerie, Suriname, where tens of thousands of people converted in the area which previously only had a few hundred Christians. We also see evidence from Yale historian Ramsay MacMullen that the leading cause of conversion to Christianity in the 3rd-4th century was healing and exorcisms, and scholar JP Moreland estimates that up to 70% of the growth in Evangelicalism worldwide over the past few decades has been linked to signs, wonders, and miraculous healing.
Throughout history, God has spoken clearly and forcefully to people throughout many nations with these glorious acts of power, expanding the kingdom of God throughout the world.