At one point someone asked me why God doesn’t blatantly show himself on the streets of a city as something magnificent like a huge powerful man, then all would believe he is God.
The fact is he did show up on earth in the first century (well a little before). Most didn't believe. But he left it to his church to pass on what Christ did. Even with the Jews, God revealed himself to those who were seeking or to those God chose. Then he left it up to them to do the work showing the people God is true, real, and good. Many of the people didn't want to go through all the trouble to even brush the surface of who God is. People leave it up to those who are more adept--most don't want to do the work of faith. (This sounds bizarre, but faith takes work and work takes faith.)
Even if God showed up as some mythical creature, there would still be those who would explain it away. Then there would be those who would fall and tremble before it in awe. Then there would be those who are skeptical that it ever happened. (Not everyone observed Christ, yet many believe and many do not and did not.) Yet God appearing as some mythical creature could propagate idol worship.
I think God wants us to have faith yes--which points to Christ. But he also wants us to do some work to discover that He is good, true, real, the God above all gods.
The purpose of faith is transformation. Seeing God walk down the street (at some time in history) will transform someone sure, but it also may not. So does faith, it will transform if one believes, it won't if one rejects that which requires faith to believe. People are so ingrained with sin, which manifests in many empirical ways, that if God were to show up who’s to say a majority of people would believe this is the One true God? Jesus who was fully man and fully divine—the Son of God—walked the streets. Some believed, others did not believe he was the Son of God.