Jesus said to her, "Do not cling to me, for I have not yet ascended to the Father; but go to my brothers and say to them, 'I am ascending to my Father and your Father, to my God and your God.'" John 20:17
This is such a powerful statement made by Jesus. The risen and soon to be ascended Son of God calls his disciples brothers, and declares his Father to be their Father.
It is also interesting to follow the transition in terms Jesus uses to describe his followers in John. He starts out by calling them servants, and then friends, and finally brothers.
I understand your hesitance at the idea of someone making God prove himself. To be sure, there are times where Jesus rejects people because they ask for a sign (the Galilean officials son in John comes to mind). But the Bible does not always speak negatively against those asking God to prove himself. Indeed, the Bible is full of stories where God's followers asked him to prove himself. For example, Gideon refuses to go to battle unless God proves himself with not one, but two fleeces (Judges 6). Saul was also hesitant when Samuel proclaimed him to be the future king - because he was from the lowliest family of the lowliest tribe - until the prophet told him that he would meet three people on the road carrying sacrificial goats, bread, wine, and the Holy Spirit (1 Sam 9-10). Finally, Moses meets God at the burning bush, and that miraculous event is not enough for him to believe that God would use him to free Israel. Instead, God basically has to lay out his whole plan for him AND rope Aaron into the process as well before Moses agrees.
There are also narratives where God used external events to prove himself. Consider the Exodus narratives. Many people read the story of the 12 plagues and think God has it out for Pharaoh. That he is somehow destined to die by his hands to make God's name great in the world. Mostly they come to this opinion because Exodus starts with God saying he will harden Pharaoh's heart. But if you look at the Hebrew, the word for "hardening" takes on a transformation after the seventh plague. With the exception of the introduction, every time Exodus mentions the hardening of Pharaoh's heart, it is always "Pharaoh hardened his heart" or "Pharaoh's heart hardened itself." That all changes, however, after the seventh plague. From that point on, it is "God hardened Pharaoh's heart." God may have known from the beginning that Pharaoh would not listen to him, but that does not mean it was foreordained. More on that later.
If you examine the length of the seventh plague narrative compared to the previous six plagues, you will notice that it is much longer than the others. Up until this time, Moses mostly shows up, tells Pharaoh to let his people go, gives the consequences and leaves. This changes, however, before the seventh plague, which is much longer:
9:13 Then the Lord said to Moses, “Rise up early in the morning and present yourself before Pharaoh and say to him, ‘Thus says the Lord, the God of the Hebrews, “Let my people go, that they may serve me. 14 For this time I will send all my plagues on you yourself, and on your servants and your people, so that you may know that there is none like me in all the earth. 15 For by now I could have put out my hand and struck you and your people with pestilence, and you would have been cut off from the earth. 16 But for this purpose I have raised you up, to show you my power, so that my name may be proclaimed in all the earth. 17 You are still exalting yourself against my people and will not let them go. 18 Behold, about this time tomorrow I will cause very heavy hail to fall, such as never has been in Egypt from the day it was founded until now. 19 Now therefore send, get your livestock and all that you have in the field into safe shelter, for every man and beast that is in the field and is not brought home will die when the hail falls on them.”’” 20 Then whoever feared the word of the Lord among the servants of Pharaoh hurried his slaves and his livestock into the houses, 21 but whoever did not pay attention to the word of the Lord left his slaves and his livestock in the field.
Then the plague comes and the ones outside die. Why give this long intro when all the others have been short? It is because God truly wants Pharaoh and his people to submit to him. If they do so, the narrative ends and the people of Israel go free.
But what about the requirement that God must "show his power" through Pharaoh in order to proclaim God's name through the earth. We know from the narrative that Pharaoh did not give in, and God showed his power and made himself known by doing 12 plagues and killing Pharaoh. As readers of the story, we assume that is the only way God could have been done it. But there is another way he could have accomplished the same goal. Pharaoh was basically a god in his country, a literal deity in the Egyptian religious cult. Egypt was also one of the strongest, if not the strongest, power in the region at that time. If God does seven plagues and Pharaoh submits and lets them go, God's name would have been spread among the nations of that region just as easily.
No, God did not want to do twelve plagues. He did not want to do one plague. He wanted Pharaoh to submit, but he did not. But some did. Later on in chapter nine, it says that the servants who brought in the livestock retained their cattle. Further on, you see that most of these people that submitted also followed the Hebrew nation out of Egypt: "A mixed multitude also went up with them, and very much livestock, both flocks and herds. (Exod 12:38)" When you add to that the fact that the plagues likely took about a year to play out (the narrative shadows this), you can see that it was God's desire to prove himself to Pharaoh so he would let his people go. If Pharaoh had relented, the world would have been shaken. I can see the conversations now:
"Did you hear that the nation of Egypt, the strongest nation around, was cowed by the God of a bunch of slaves within the country?"
"What? No, tell me more."
"Yeah, this God did seven plagues to prove himself and the Pharaoh converted to their religion and let them go. He even paid them to go and helped them out of the country."
"Insane. What was he thinking. That God must be really powerful."
"I know."
In my experience from reading the Word and seeing it lived out in real life for several decades, it seems that God refuses to prove himself with signs for those who should know better than to ask for a sign for things that faith should cover (i.e., established Christians who should have faith figured out by now but persist in willful ignorance by constantly asking to god to re-prove himself). [This is not to put God in a box; he is so merciful!] God does, however, seem to give signs for great events or to convince baby Christians or non-Christians that he exists. To those I give that challenge, by saying that prayer and reading John every day for three weeks, they are submitting their will to God's will. That gets God's attention!