Or maybe, just maybe, it's simply the case that you are clueless about what Islam teaches about eschatology and soteriology.
Just ponder for a second about how
ridiculous the belief in God, particularly one that reveals stuff, is
if it is not explicitly and implicitly attached to the concept of Salvation, defacto.
As for Islam's eschatology, there is a heaven and hell,
https://en.wikipedia.org/wiki/Jannah
This is Islam 101, it's insane you don't know about it.
Just imagine believing that there is a God and believing that the ground is the end of everything, how many religions teach this? zero.
Believing in Jesus is irrelevant to the supposed conundrum which you have spewed up yourself. Jesus is salvation with extra strings attached. It is God = Salvation + belief in Jesus.
Judaism certainly doesn't need Jesus for salvation, that would be a fundamental contradiction in the nature of God itself (YHWH) as per Abrahamic tradition, Jewish or not.
All you have done is allude to one of the many endless problems with Christianity, the Christian salvation doctrine is fundamentally nonsense, essentially and categorically.
Sacrifice for salvation is an impossibility and an absurdity given all of the preceding Old Testament context. If the righteous people in the Old Testament go to heaven, then Jesus' sacrifice meant nothing. If people go to hell for rejecting Jesus in this life, then Jesus' sacrifice meant nothing. It is an impossible paradox. It could only be solved by some form of universalism wherein Jesus' 'sacrifice' liberates all of creation back to God henceforth making belief and disbelief irrelevant, which is of course a much despised view by most Christians (even in light of the 'problem of evil').