Whatever the spelling - Moses or Moshe; Elias or Elia; Jonas or Jona - the person I'm addressing will know who I'm referring to. This is because, when replying to their post, I use the same spelling they do (unless their choice of spelling is manifestly incorrect; in which case, I would suggest an alternative - with reference to an appropriate source). Does this satisfy you?
Nothing! Okay. If writing to a Christian I would use 'Moses'; to a Jew, 'Moshe'; and to a Muslim, 'Musa'; I would do so because these are the spellings in their respective Scriptures. Seems only polite to take account of this.