Without going into a detailed answer to you can I just point out a few things ...
1 "I don't know" is a good answer, it is far superior to making up the answer. If we knew everything, science and research could be ended.
2. Atheism doesn't have to be proven, atheism is simply a lack of belief in gods.
3. Atheism says nothing about miracles. However, science do not accept miracles as an explanation. Miracles can either be explained (such as the many examples of weeping Madonna statues) or have no evidence that they ever happened
4. Regarding the Einstein quote, can I refer you to this page ...
https://fakebuddhaquotes.com/debunking-fake-albert-einstein-quotes/ which explains that Einstein never said such a thing.