Why Shirk Is Unforgivable
God is merciful for those who deserve mercy. They try to do good but commit some mistakes. The rebels on the other hand, deliberately commit a major and blatant sin whether they are polytheists or murderer etc they are not forgiven. Polytheism is an assertion or claim that there are more than one God. This assertion has no argument, no knowledge, it is but a lie. When a person insist on keeping it despite having no justification, he denies God and his own intellectual and his consciene. Thefore he deserves no mercy.