Complex sentence: The death is significant as Bahá'ís believe that Bahá'u'lláh offered him the chance of being cured, however he chose to use his life as a sacrifice so that the close imprisonment of the Bahá'ís would end.
Split into simpler sentences: The death is significant as Bahá'ís believe that Bahá'u'lláh offered him the chance of being cured. However, he chose to use his life as a sacrifice so that the close imprisonment of the Bahá'ís would end.