They would have had no persuasive reason to accept a lie that Jesus's body was gone/missing.1
No plausible candidate liar(s) existed. After all…
• …In general, no early Christian would even try to spin such a lie to other Christians.[Forthcoming]
• …The liar would have rightly expected his lie to fail, insofar as the liar would be aware of the information articulated in the point above.1
The Jerusalem church's belief was actually grounded in Mary's testimony.1 This is relevant because Mary's autobiographical report that she discovered Jesus's tomb empty was not a lie.