The primary issue for me is that while I believe that evil acts can and should have consequences attached to them, I do not believe in the concept of afterlife punishment per se.
Judaism has no doctrine of Hell, or of eternal damnation, like Christianity does-- and if I recall right, I think Islam has some variation of the concept also. There is a doctrine that some embrace called Gehinnom, which is technically not a Hell but a Purgatory: souls who die with unresolved sins (which is most, if not all, souls) are said to spend a finite duration in Gehinnom "working off" their sins. Even among its adherents, there is no agreement as to precisely what happens in Gehinnom, but the general agreement seems to be that it is unpleasant, and some of the more...extreme...versions of the doctrine paint very gruesome pictures indeed.
However, many of the theological strands that are core to my understanding of God are those which reinforce strongly that God is infinitely merciful and forgiving, and makes endless room for people to repent for wrongdoing. Afterlife punishment, IMO, is incompatible with such a God.
Yet I still believe that evil deserves consequences, and even a loving God would see that such consequences occur. How to resolve the quandary?
Added to these issues are my belief that God created us-- among other purposes-- in order to gain deep wisdom and compassion, and to teach the same to others; which I do not believe that most people sufficiently accomplish in one lifetime. Also, Jews are commanded to keep all 613 commandments, yet this is impossible in any one lifetime, as some are for men, some for women, some only for kohanim (levitical priests) and levi'im (levites), some only function during the time of the Temple, and so forth. Thirdly, while I believe strongly in human free will, I also believe in something along the lines of a divine plan-- yet those seem to be irreconcilable to one another.
My resolution to all of these is
gilgulei neshamot.
If a person sins and dies before completing
teshuvah (the formal process of repentance for sin, which includes not only confession to God, commitment not to do the same thing again, and participation in Yom Kippur, but also in apologizing to wronged parties, admitting guilt and accepting consequences of one's actions, and making any and all possible reparations for what one has done), they have a "debt of sin" on their "cosmic scales." This "debt of sin" can only be balanced out by accomplishing positive actions that inversely parallel the negative actions done in a former life. So one is reborn and reborn again until one has not only balanced out the negative actions of former lives with positive actions, but one has "tipped the scales" in favor of positive actions.
At the same time, if one is Jewish, one is also reborn as many times as is necessary for one to complete all 613 commandments.
And one is also reborn as many times as is necessary for one to voluntarily and of free will choose to do whatever action or actions the divine plan calls for us to do.
Finally, one is born and reborn as many times as is necessary to maximize one's attainment of wisdom and compassion. At that point, one can choose to move on, out of the cycle of rebirth, into Olam ha-Ba (The World To Come, essentially our version of Heaven), or to continue being reborn in order to pass on what one has learned-- the memories of which constitute part of our primal subconscious, never to be fully recalled in clarity during any particular lifetime, but serving as the most foundational layer of our primal psychological impulses.
Sooner or later, as I construct this theology, I assume that everyone is capable of moving on to Olam ha-Ba. No afterlife punishment is necessary, because rather than punishment, one is given potentially infinite opportunities for
teshuvah (de facto if not de jure), and what is more, infinite opportunities to learn from their mistakes, which is something afterlife punishment cannot accomplish.
Probably the best basic and simple summary online that I've seen is the one at
Jewish Virtual Library. Though of course even that misses a few of the more complex elements and sundry variations of even classical ideas of
gilgulei neshamot; and my version is slightly different than any of those.