Shefaah (sheh-fuh-uh, from Arabic), is a request to favor some needy. The case is among,
This-worldly cases are understood, trivially. The other worldly shefaah is not what we witness, yet. But what we know, from hadiths and the Quran, is sufficiently informative.
Baqara(2):254-255 (that is, combining 254 & 255), provide the key point. Shefaah exists, but some might find that to be unavailable. Their laxness about (or, opposition to) the commands and suggestions of Allah, will slap back on their faces when they will find shefaah not available.
The luck for shefaah is to know that none else but Allah has the right to be worshipped.
The more you understand this, the more you might expect shefaah (and sooner).
True understanding is your principled living to the level of your know-how. (Otherwise, if living as if ignorant of the point (or, opposing), then that might not help favoring you.)
Obeying anti-Islamic something is bad. The Quran is pointing out that, even in some worst case: "Wasn't the Earth of Allah wide? Why were you staying under tyranny?"
Shefaah is not only on the Judgment Day.
Equivalently, lots of tawba (remorse&resolution, repentance) is available while living.
Some of the people who will go to hell, then will get out of hell with (eventual) shefaah.
Allah is the Creator of the Universe. If He were minimalist, He would not have created the Universe, in the first place. Thus, the grand nature of the Judgment Day proceedings, and discussing our life histories there, is just natural. Shefaah, is a fitting, lovely thing, likewise.
Allah is the exclusive source of shefaah. Enam(6):51 (The point is worth stressing, because polytheists might hope invoking "angels"/etc against Allah, but angels are totally obedient to Allah. Nebe(78):38.) No shefaah might exist, unless Allah will allow.
Allah might or might not forgive people's sins (with or without anybody's intercession).
Allah will not forgive, if there is a victim -- unless the victim will forgive, too.
A hadith is telling about some (lieing, abusive) people who will face hostile-shefaah.
Animals' rights, are not overridable by shefaah [ of Muhammed (s.a.s.), or at all ].
If a victim has no way to get out of hell (nor lessening), he/she might be like animals. But only Allah knows the cases fully. I have no sure formula to account for all cases.
If the victim is a human, Allah might opt for shefaah. (Not forgive by Himself, but shefaah.)
A case from a hadith is known that, a man is on the edge. If he will pay his debt to a victim, will go to hell (because his account will fall to negative). Then, Allah intercedes, offering to the victim a mansion in heaven, thus both friends get into heaven together.
((Note: While on bibliographic quest, I have not located this hadith @ Bukhari (while writing this). But, I recall well that, for example, EsadCosan (rh.a.), & M.Z.Kotku (rh.a.) tell of this hadith in radio talks.))
Shefaah is thus, good for Allah to express more of His mercy (without succumbing to a leniency to oppressors, which would presumably violate the mercy to the victims, now).
If you would not like to burn your hand in oven, you know that nobody wants to waste even a single second in hell. Thus, shefaah is a big help to the needy/guilty, and no problem for the rest of us, because no victim of that person went unpaid -- presumably, mostly, by his/her own positives (until falling to that bankruptcy point).
Thus, what I'm maintaining is the fullest sense of shefaah. Not only ceremonial or symbolic.
Allah weighs the offenses, then lessens (out of the punishment). That is the fullest harmony with the entire enterprise of weighing sawabs vs. joonahs (positives vs. negatives). Why would faith or love not count?!? That is what shefaah accounts for.
Shefaah is not only a "love bribe" such as when newborn babies come with a "gift" to their siblings. Inferrably, shefaah is for a person who heeded a person worth heeding. Foremost cause is the heeding of the prophet of Allah, they know. (Muhammed (s.a.s.) is the final prophet, who is valid in our times, till doomsday. Jesus was the previous.)
Having a few aspects that would count ceremonial, is nothing for undermining the shefaah process. Even in this world, lots of what we do, is with ceremonies, too. Informative gestures (or, customs) provide the context for valuable processes. (Sitting around a table, is not only a ceremony, if food is next. Sitting in desk, wait a lecture.)
A tricky point to discuss, is the case of destiny. If "sin" was unavoidable.
No path for good after a point (Hadid(57):22), although there might have been priorly (Sura(42):30). Then, Allah might "intercede" with His own (otherwise regular) law.
Furthermore, there were the (prophetless) people who had no chance to heed a shefaah-source.
Their lifestyles might resemble that of the (faithful) sinners, but they have nobody to invoke shefaah in their favor. Then, Allah might invoke shefaah, for such "lost" people.
A hadith is listing shefaah sources, and finally He is invoking His further shefaah. That hadith might justify the talk (theoretically). But presumably, all of this talk, is (practically) a waste, because now that you know about Islam, you need to convert to Islam. That talk is inferrably about ignorant people, who passed away, without knowing Islam, truly.
Requesting a hell-proof status, with your mere philosophy, is a wishful thinking -- and denial.
For example, questioning "why atheists/etc go hell, if not otherwise criminal."
Lots of mercy is automatic. But that might not suffice, when you keep committing sins.
There, Muhammed (s.a.s.) is to help muslims. That is the system of Allah. If He would like to, He could neglect all sins, then there would be no need to have extra shefaah, either. Inferrably,
The more you worship only Allah (the less your sins), the less the need to wait shefaah.
The tension of waiting for shefaah, is a punishment, too. Some worse cases literally go to hell, then getting out, but relatively good cases will have the tension of the Judgment Day, too. Huge time, with your knowing your sins (small or big), and stress.
Thus, Allah has a multi-step process of punishment. Shefaah is a theme in that process, and contributes lots of irony and mercy. Favoring love of muslims. Fair.
After Muhammed (s.a.s.) acknowledging Him the first (in pre-Universe time), he (s.a.s.) is having the right to shefaah for starting the Judgment Day court proceedings
For starting the court sessions, the role of the intercessor (shefaah) is of Muhammed (s.a.s). Thus, that is his (s.a.s.) helping role to all of the people, while that is needed.
For his (s.a.s.) mother, he (s.a.s.) was not allowed to pray. I might not guess, whether that was because his (s.a.s.) praying has a high value. (Perhaps, she will count in the category of faithful (or, ignorant), as far as she understood, before Islam.)
In the case of the (somewhat) stubborn uncle who refused Islam (Abu Talib), his (s.a.s.) hadith does not hope getting him out of hell into heaven, but hoping the fire to boil his brain -- that sounds to wish killing him (or, coma), because pain-receptors are in the brain. That is the example of type of the best hope, in the case of some stubborn type (or, was sheepish with anti-Islamic types), who passed away as a non-muslim.
Hadiths warn about some specific behaviors, which make shefaah unavailable to the offender.
Like not paying the zekat, while due. The Quran is listing zekat, in that context. Hadiths relate to shefaah, too. Not paying the zekat, is equivalent to theft from a poor.
Hadiths suggest a few shefaah-promoting activities too.
For example, to pray that Muhammed (s.a.s.) will have the right for intercession (and the maqam-ul-mahmud, etc.) will be his (s.a.s.), is cozily understandable in the sense of Allah promoting muslims to love muslims (most so, for Muhammed (s.a.s.)) , as well as for expressing support/thank to what Allah has already told as the upcoming gift.