I understand that we have free will and are punished for doing things that hurt others, and are rewarded for doing the right thing. What I do not understand is, why does Hashem send us to Gehinnom for something that does no harm like carrying on Shabbos? I get that we can be rewarded for following it, but unimaginable torture for not doing so seems harsh. Additionally, we are put in this world to follow 613 commandments with tons of detail for each one that nowadays it is almost impossible not to be sinning against one of them. I have heard that Hashem created us out of pure goodness and kindness to us, and I would like to know what that means given all the punishment.
The Ramban in Devarim 22:6 states that the mitzvos are for our own good. Hashem gains nothing from any of them.
אבל אלו ההגדות אשר נתקשו על הרב כפי דעתי ענין אחר להם, שרצו לומר שאין התועלת במצות להקב״ה בעצמו ית׳, אבל התועלת באדם עצמו, למנוע ממנו נזק, או אמונה רעה, או מדה מגונה, או לזכור הנסים ונפלאות הבורא יתברך, לדעת את י״י. וזהו לצרוף בהן – שיהיו ככסף צרוף, כי הצורף הכסף אין מעשהו בלא טעם אבל להוציא ממנו כל סיג. וכן המצות להוציא מלבנו כל אמונה רעה, ולהודיענו האמת ולזכרו תמיד.
...They have no benefit for Hashem himself, they are for the benefit of man himself: to stop him from being damaged, bad beliefs, bad qualities, to remind him of the miracles Hashem did, to know Hashem. They purify him [the person], like one who refines silver by melting it to remove the impurities, so too the mitzvos remove our impurities. And also the mitzvot remove bad beliefs and teach us truth to remember always.
Therefore not only do we do harm to others when we sin, but we actually distance and destroy our connection with Hashem. We damage ourselves too! Hashem is constantly trying to shower us with all good, but we distance ourselves with our free choice. (See Ramchal Derech Hashem Chapter 4:10)
Gehinom is there to purify us from this harm.
Please see Chagiga 15b. Acher a sage sins horribly, he may not enter the world to come because of the sin, he may not enter punishment because of his Torah. Rebbi Meir mentions it would be better for Acher to face judgement (ie: Gehhna smoke pours from Acher's Kever) so that he should be able to enter the world to come. And that is precisely what Rebbi Meir causes to happen. We see a clear example (imo) that the "punishment" is for our benefit as well so that we may enter the world to come. Acher was not allowed to enter that world since he sinned, but after his punishment he is. The sin has been purified.
Also the punishment is limited in duration (12 months) See Sefer HaIkarim 4:38.
Also a number of commentators state explicitly that Hashem does things in an infinite way, gehinom (punishment) is limited because it precisely does not come from Hashem. Hashem does NOT punish us. We cause the punishment to come upon ourselves. (See 1st Perek of Tomer Devorah, and Rav Yaakov Mlisa on Eicha: לא תצא מפיו הרעות והטוב)
In theory Hashem is kind and allows this purification, had he not, that imo would be much more cruel.
In this world, we have an opportunity to serve Hashem. For the rest of eternity, He's going to be looking after us, and there won't be anything we can do for Him.
When it comes to Hashem as He relates to His creation, He absolutely needs us to not carry on Shabbat,
צרך גמור הוא1. By not doing so, we are serving Him, by doing so, we are ruining the whole world.
To Him in His Essence though, it is technically true that details like carrying a physical object in a particular space or not makes absolutely no difference to Him2, He is
שלימתא דכולא3. However, something far more sublime matters to Him in His Essence - the refinement of mankind. So even in His Essence, He needs us to become refined, and that is done by keeping His Mitzvot4.
So, we are avoiding carrying on Shabbat because He needs that, not because we need it. He really does need it, He's not going to change5 or budge on that6, and when one passes the point that one can no longer do that for Him, even though they had ample opportunity to do so, or worse: they violated it, then one will experience gehinom, which is regret and shame in full force.
So this is the correct attitude: Hashem needs you, and that means all of you; every last detail of your life has a right way to do it, and a wrong way to do it. Judaism is not harsh though. It fully recognises that what is expected of us is very trying, and is very understanding. There is teshuva, there is pesach sheni, Yom Kippur, mens rea requirements that are very steep, 13 middot of rachamim, and every extenuating circumstance is taken into account.
Still, after all that, once we've finished being silly, we are going to feel very embarrased and we will all need a hot shower in gehinom. He doesn't "send us" there, in fact, He has to come with us. That's part of why it's so painful and the real meaning of fearing Him7, but B'H in His great goodness, it can't last more than a year. It's not a punishment8, it's just reality, and a testament to how great Hashem is and how much He expects of (and believes in) us.
1 - לא תהי׳ משכלה תשי״ב, ב
2 - Bereshit Rabba 44:1
3 - Tikkunei Zohar; Introduction, 17b et al.
4 - לא תהי׳ משכלה תשי״ב, ד; see also בשעה שהקדימו, יום ב׳ דחג השבועות תשי״ב, and Zohar Bereshit 16, and many other sources
5 - Bamidbar 23:19
6 - 9th principle of faith of the Rambam
7 - See Tanya Ch. 36
8 - See Chovot Halevavot 1:10 for example
Please note the only commandment that is explicitly mentioned in the tora that is connected to shabbat are Keep my Sabath, and don't light a fire.
Everything else is Derabanan not directly from hashem.
Yes, There are those fanatics that will throw to you that WHAT THE RABBIS DECREE IS MI-SINAI and HASHEM SAID It's like he ordained it.
At the very end, what was mentioned in the tora one can't add or remove, though it only takes a Possek to change to a degree what the rabbis decree.
There's a book called (The Narrow Halakhik Bridge By Rabbi Ronen Neuwirth)Haskama from Chief rabbi of Shoham, and Rabat Gan.
He says explicitly the majority of the laws that are spoken are rabbinical and not for the sake of heaven, rather for the sake of this world i.e Law is legal not necessarily logic) lets take an example, Electricity on shabbat, 99% percent (politically) say it's forbidden, though a son in law of rabbi Eliyashiv (rabbi Zalman Aurbach, disagrees and permits it). To this day there's a rabbi by the name of Rabbi Chaim Ovadia, the Grandson of Grand Kabbalist Rabbi Yehuda P'taya, and whom is also a student of the former chief rabbi of Israel, Rabbi Mordechai Elyahue, permits electricity on shabbat, (Albeit with other restrictions), another example, can't mix milk and meat, right? Correct, so why cant I have a chicken burger sandwich cheeseburger with real cheese? I learned with a big mass-mid that A rabbi Yose and his whole city ate chicken and milk together. And all-phi Halacha I may get a Cold cut and have it with real cheese. So Halacha Is very political, not really spiritual. I was told even The ARIZAL stayed FAR away from teaching Halacha as it's very subjective not Objective, (NOT a banana republic, just not as we perceive it to be as so heavenly).
So Don't fret, You'd be surprised how far a simple honest life, will take you in heaven. Just find ( Or develop your own logical hashkafa) have a raw to guid within it, and you're good to go.
I know this answer is going to get a lot bad remarks and down votes because it goes against the norm, so in the end, it's truly up to you.
If you need help or clarification im more than happy to help.