No one ever thought that the concept of sin is the way of the church to enforce laws through fear?
Then it makes sense suddenly that blasphemy is such a bad sin,for it is what undermines the authority of your spiritual leader the most.
It is quite clever to declare natural feelings everyone has and which are accepted as being not positive as sins, like lust or wrath.
So that makes everyone a sinner and the only way to not end in hell is to live a faithful life so that your sins are forgiven.
And a faithful life means following the rules of your church.