I can only think of two places in the New Testament where people are excluded from salvation.
One is where Jesus declares that one who speaks against the Holy Spirit will not be forgiven. I honestly don’t know exactly what that means but have been told by those who understand these things better than me, that if you wonder about your having committed that sin that means you haven’t.
Also the Apostle Paul states about certain sinners, particularly those who practice homosexuality, that they will not inherit the Kingdom of Heaven.
“Also the Apostle Paul states about certain sinners, particularly those who practice homosexuality, that they will not inherit the Kingdom of Heaven.”
... he included more than homos in that passage...
You might actually want to read the New Testament in a bit more detail.... John 3:18 He that believeth on him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God.
The fifth pillar of islam is to accept the literal koran. To be a moolsem means to accept all 5 of the pillars.
Here is a link with the best explanation I have heard for the unpardonable sin which is unbelief. It has to do with the stoning of Stephen
http://lesfeldick.org/lesqa-c.html#6c