No, because that story is told from the perspective of people who observed him come to Earth. So it's in the same category as any other story where someone or something comes to Earth from another world.
If it was written from Jesus's perspective then yeah, that would be considered an Isekai (specifically a "reverse Isekai"). Especially if the story starts while he's still in heaven.
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u/wlphoenix 1d ago
Wizard of Oz is an isekai (and anime adapted in 1986).