Perhaps, Mother Teresa could have shoved the whole issue aside towards the end of her life as it is not significant. Her passion, as i see it, is to help the destitute poor.
Perhaps she dwelled more on her joy of being able to gather like minded people in her charity mission to assist her in achieving her most 'Karunic' mission.
The Buddha did mention, as found in the Dhammapada that "He rejoices now, He rejoices hereafter, Recollecting his virtous life."
Well that's what I would like to believe Mother has achieved. And this makes the whole issue of whether her god exists or not insignificant.