Stephen, my late wife's childhood had a lot in common with your childhood. Her religion also required the memorization of Cathechismic responses, a liturgy that only discussed certain passages of scripture, and they were also told what they were to believe and were not encouraged to search the scriptures to see whether these things were so. (Acts 17:11)
Instead of being taught that all men are fallible and only the scriptures are infallible, they were taught that the doctrines which their religious organization taught were the correct doctrine and were discouraged from questioning that doctrine.
The reason that I wrote the above two paragraphs is to make certain that you will understand that in the rest of this post I am fully aware that much of what I am about to relate to you is new information to you.
Consider with me the things which these men had seen and heard.
They had seen all the water in their vessels and all the water in the ponds and rivers turn to blood and they had seen that all the fish in the river died and that the river stank from the blood and the dead fish. Exodus 7:19-24
Their houses and their ovens and kneading bowls had been invaded by frogs. Then the frogs had abruptly died leaving their corpses everywhere. Exodus 8:3-4, 13-14
They had been covered in lice. Exodus 8:17
Then something even more amazing had occurred.
The whole land of Egypt had been covered in flies except for the secction of land in which they dwelt. Exodus 8:21-23
Then the cattle, horses, donkeys, camels, oxen, and sheep of the Egyptians all became very sick but again the animals belonging to the Israelites had remained healthy. Exodus 9:3-4
Then all the Egyptians had broken out in boils and sores but the Israelites had remained healthy. Exodus 9:9
Then a great hailstorm worse than Egypt had ever had before came upon Egypt but again the Israelites who lived in a section of Egypt known as Goshen had no hail fall on them. Exodus 9:22-26
Then a locust invasion had destroyed all the crops of the Egyptians. Exodus 10:12-15
Then a great darkness covered the land of Egypt for three days but the place where the Israelites dwelt was not covered in darkness. Exodus 10:21-23
Then all the firstborn sons of the Egyptians had died in one night but in the houses of the Israelites who had followed the instructions they had been given, the firstborn remained alive.
Then a giant pillar of cloud had appeared in the sky which they followed but at night this same object in the sky turned to fire and gave forth light so that they could see where they travelled. Exodus 13:21-22
Then they had seen the waters of the sea (probably either the gulf of Suez or the guld of Aqaba) part and form a pathway. The cloud which they had been following passed behind them and stood between the Egyptian army which was pursuing them and was a light to Israel and a fog to the Egyptians. The land between the two walls of water allowed the animals and wagons of Israel to cross with no major impediment but God had caused the chariots of the Egyptians to be hindered. Exodus 14:19-25
Then as soon as all of Israel was on the far side of the sea, they had seen the waters close over the Egyptian army.
Then another strange thing started happening. Six days a week, an edible substance started appearing on the ground. This substance could be boiled or baked. If they tried to keep it overnight, it became rotten and worms appeared in it. Except on Fridays. On Friday if they kept it overnight till Saturday, it was fresh and edible on Saturday. It also did not appear on the ground on Saturdays.
Although they had been travelling for years prior to this rebellion, none of their shoes or their clothing had worn out. In fact, the clothing and shoes remained in good condition for forty years.
Then they had seen water come out of a dry rock. (This was not the time that Moses sinned against God that occurred about 39 years after this event.) Exodus 17:5-6 (Note: Only some of Israel had seen that there was no spring of water in this locale prior to this event. So it may be that some of them were not sure that this was a brand new spring.)
Then they had seen what God did to Mt. Sinai.
there were thunderings and lightnings, and a thick cloud on the mountain; and the sound of the trumpet was very loud, so that all the people who were in the camp trembled. And Moses brought the people out of the camp to meet with God, and they stood at the foot of the mountain. Now Mount Sinai was completely in smoke, because the Lord descended upon it in fire. Its smoke ascended like the smoke of a furnace, and the whole mountain quaked greatly. And when the blast of the trumpet sounded long and became louder and louder, Moses spoke, and God answered him by voice. (Scripture taken from the New King James Version®. Copyright © 1982 by Thomas Nelson. Used by permission. All rights reserved.)
Then they had heard God speak forth the ten commandments. Many people know that God gave Moses a written copy of these commandments written by God on two tablets of stone, but a lot of people seem to be unaware that before God gave Moses those tablets of stone, God first spoke those commandments so that all of Israel could hear Him.
The people became scared and they begged that Moses would speak to God and that God would not speak to them. Exodus 20:18-20
Two other places where it is recorded that God on this occasion had spoken to all of Israel are Exodus 20:22 and Hebrews 12:19
Because I am getting tired, I'm going to only give two more examples, both of these involve the relatives of Moses and Aaron.
God had decided to make Aaron and his sons priests to God, but before this could take place first Jehovah's tent had to be erected. All of what I'm about to describe took place in less than 2 weeks. In Exodus 39 and 40, it states many times as Jehovah's tent is being set up by Moses: "As Jehovah had commanded Moses."
Then came the ceremonies by which Aaron and his sons were to be consecrated. This consisted of some things Moses was to do to them on the first day, then they were to remain in the entrance of the courtyard of jehovah's tent for seven days and then there was another set of things that were to be done when those seven days were complete. (For brevity's sake, I'm simply summarizing.)
Note: There are no chapter breaks in the original text. The chapter breaks are artificial and do not indicate a change in time or circumstance unless the text itself says so.
Remember what I said about Exodus 39 and 40. This same thing occurs in Leviticus 8 and 9.
As Moses and Aaron are doing the things that God had commanded them to do, they go into Jehovah's tent, then come out and bless the people.
Suddenly the glory of Jehovah appears to all the people and a fire comes forth from God and without any act on the part of man consumes the animal and fat which had been laid out on the altar to be a burnt-offering to God.
When the people saw this happen, they gave a great shout and fell down on their faces
But then something dreadful happens in the sight of all those who were assembled to watch the consecration of Aaron and his four sons. Two of Aaron's sons without any instructions from their father, from their uncle Moses, or from God, took their censers put incense in them and took fire and lit the incense which thing God had not given any instructions to them to do. In the presence of all who were assembled, fire came out from before Jehovah and killed the nephews of Moses on the spot. Leviticus 9:23-10:2
The other thing that they had all known about was what had happened to the sister of Moses and Aaron. Moses had married a woman who was not of the children of Abraham. She was a daughter of Cush. Cush was one of the sons of Ham. For some reason, the Bible doesn't say what the reason was, this had upset Miriam and Aaron.
(BTW, God did not object to "inter-racial" marriages, but He did object to Interreligious marriages. The ancestry of Jesus found in Matthew 1, lists three women who were not descendants of Abraham. Tamar was a daughter of the land in which Judah was living. She was a gentile. Rahab was a gentile of the city of Jericho. Ruth was a gentile of the nation of Moab. These three are the only women mentioned by name in Matthew's account of Jesus' lineage except for his mother, Mary.)
Because Miriam was upset at Moses, she had questioned his authority.
God had called all three of these siblings and told them to gather in front of His tent. Then God's glory had descended in a cloud and had told Aaron and Miriam to come forward.
God's voice had spoken and said:
Hear now my words: if there be a prophet among you, I Jehovah will make myself known unto him in a vision, I will speak with him in a dream. My servant Moses is not so; he is faithful in all my house: with him will I speak mouth to mouth, even manifestly, and not in dark speeches; and the form of Jehovah shall he behold: wherefore then were ye not afraid to speak against my servant, against Moses?
The cloud of God's glory and then departed and when Aaron looked he saw that his sister, Miriam was completely covered in leprosy.
Although God had listened to the pleas made to Him and had healed her of her leprosy, He had said to Moses:
If her father had but spit in her face, should she not be ashamed seven days? let her be shut up without the camp seven days, and after that she shall be brought in again.
During those seven days, the Israelites had remained where they were camped until she was healed.
Tiredness has limited the number of examples, I have given. I have not for example, written of the men who had eaten a meal in the presence of the glory of God in Exodus 24.
The point I am trying to make is that these men who rebelled had plenty of evidence to prove to them that Moses wasn't doing these things, Aaron wasn't doing these things, God was.
They had also seen how God responded when people became presumptious and acted without his permission.
If someone tried to climb the White House fence in order to visit the President what would happen to that person?
Likewise if someone without first receiving permission from God acts presumptiously with relationship to the things of God that is like Lèse-majesté and God will not tolerate presumptiousness.