Question: where in the bible does it say blasphemy is unforgivable?
Answer: Several passages in the New Testament are frequently interpreted as referring to the unforgivable sin: Matthew 12:30-32: "Whoever is not with me is against me, and whoever does not gather with me scatters. And so I tell you, any sin and blasphemy can be forgiven. But blasphemy against the Spirit will not be forgiven.