As I mentioned, my two eldest grandchildren asked two very fundamental questions at our seder this year: (1) Why do we need both the מכות and קריעת ים סוף; shouldn't one be enough to prove that HaShem runs the world? (2) Why did HaShem give them the idea of עבודה זרה in the first place? I gave them an answer, but then I saw the first question discussed at length in the hagada arranged by R' Matisyahu Salomon, shlita. As it turns out, Kayin and Hevel also had this question; Kayin's conclusion led him to bring the worst of his crop as an offering to HaShem; Hevel saw something deeper and brought the best of his flock as an offering to HaShem. I believe that this difference also brought Kayin to murder and עבודה זרה, so it is all really one thing.
By way of introduction: we took the kids to a mall that specialized in unique and hand made crafts. One store was a glass blowing shop, where they also offered an opportunity to make your own glass. I am fascinated by glass blowing and really wanted to sign up and make a kiddush cup, but it was pricey. My daughter told me she also thought it would be cool and my son-in-law noted that it really wasn't that pricey for a becher. Ok... I was sold. Besides having a becher that I actually made, it is also cool because I don't have to tovel it. This glass was never owned by a non-Jew. Of course I had help (in fact, I was really the helper to the master glass blower), but still; I am really looking forward to making kiddush with my own glass that I personally created for that purpose.
So I got started making the glass. You start with molten glass -- approximately 1400° C to 1600° C. I followed the teacher's instructions very carefully. As I explained to my grandchildren (who were disappointed that couldn't help), that liquid glass could burn right through your skin (that image quelled their disappointment). It took about 20 minutes to make the glass (I can share the video, if you like). I wanted to take it home, but he told me that it had to cool down (yes, cool down) in a kiln at 950° C for a few hours!
Let's think about this. If all you want is a pretty glass, go buy one; save yourself money, time, and the danger of working closely with molten glass. But I didn't just want a glass; I wanted to enhance my kiddush by creating my own glass specifically to beautify the mitzvah. That, in fact, is the difference between Kayin/Egyptians/מכות vs Hevel/Klal Yisrael/קריעת ים סוף. Both understood that that HaShem is powerful and therefore deserving of respect. Kayin/Egyptians just wanted to do whatever was required to not get hurt. Hevel/Klal Yisrael, though, wanted a close and loving relationship with HaShem. Of course that comes with danger -- that's the nature of great power, but it is worth it.
I would like to add that the fear of Kayin/Egyptians by nature separates them from HaShem and therefore leaves an opening to believe that could be other powers that also need respect and perhaps can be used for one's own purposes; עבודה זרה. The fear of Hevel/Klal Yisrael is a fear that stems from love and therefore brings one to a relationship with the Creator; there is no room nor even thought of any other power.
Just so you don't think I have a sterile, philosophical relationship with my grandchildren: my oldest granddaughter turned nine this year. That's not a little kid anymore, that's a young lady. I told her that and she agreed. I then said sadly, "So I guess I can't carry you up to bed anymore." She looked at me and said, "Oh yes you can!", and jumped into my arms. There's nothing like being a zeidy.