No, this is incorrect. John warns us that there is sin that cannot be forgiven and that we should not pray for those caught in this sin.As an example, false prophets and wolves who use Christianity to gain money are beyond redemption.
the only unforgivable sin is the sin of unbelief. Anyone who dies as an unbeliever is unpardoned. ALL other sins can be forgiven- if the person repents of them before death and claims Jesus as the Redeemer (because it was His work on the cross which pardoned the sins in the first place.). Mark 3:22-30 and Matthew 12:22-32, John 14:6.