Through knowledge.
.
Blasphemy against the Holy Spirit is when someone accuses Jesus Christ of performing miracles, signs and wonders through the power of evil spirits, eg Beelzebub. JC is no longer physically present on earth performing such. So, it is no longer possible for anyone to commit this unpardonable sin.
OTOH, while suffering for their sins/evil-deeds, those who curse God/Jesus/Spirit and die will not be saved from hell, eg JOB.2:9.
When people commit sins/evil-deeds/law-breaking, bad things will happen to them on earth, as per DEUT.28:15 and 1JOHN.5:16.
When people do not believe in Jesus the Christ/Messiah, they will not be saved from hell when they leave this earth or die.(JOHN.3:16)
Ideally, people should shun evil by keeping God's Law and believe in Jesus Christ.
....... Bear in mind the Gentile Christians only have to keep the laws of Moses which are not a burden, especially morality laws, eg the Ten Commandments(EXODUS.20), DEUT.18:9-14, etc, as per ACTS.15:24-29.