Let me start with the calendar because I actually had to look up the history of calendars (which was super interesting). The first person to use A.D. was a monk called Dionysius who used it around 525. In the Roman empire years were counted by the year of the current reigning Consul. Dionysius wanted to avoid using the calendar based on Roman emperor Diocletian who widely persecuted christians. This new system was adopted by the church only.

Centering the calendar around nativity of Jesus was only adopted as an official calendar by Holy Roman emperor Charlemagne in around 1600, and the rest of the world changed over to it over time until around 1900.

So the people actually living in 1 A.D. had no idea they were living in the year of the lord.

As far as I know we only really know that Jesus was a real man in the Herodian Kingdom at the time and that he was in fact crucified around 33 A.D. (which would not have been called A.D. at the time). Weather we believe he was truly resurrected is more of a question of faith, relying on religious sources. So basically applying Occam's razor I would say that the resurrection was just part of the religious texts written by monks, not necessarily something that was 100% true.

In maths there are definitely larger and smaller infinities. Take for example the set of all natural numbers [1, 2, 3, ...]. This is an infinite set. Compare this to the set of rational numbers, these can be expressed as a fraction of two natural numbers [1/1, 1/2, 1/3, ...]. There is already an infinite amount of rational numbers between 1 and 2, making this an uncountably larger infinite set. All this being said, the boulder thing always sounded a bit weird to me but it does raise the question of what we mean by omnipotence, and can we accept the existance of such a being, all of this gets very philosophical. (the paradox has several proposed resolutions if you are interested btw, some more satisfying than others)

Which brings us back to the problem of evil. Let's say our lives on Earth are just a test to see if we are accepted in heaven. This explains why bad things happen as they are a test of faith. But this just raises more questions:

Why does it take God our entire lives to decide whether we are accepted? What about babies that die during birth or shortly after? How can they prove their faith?

Anyway, this got way too long. I'd like to reiterate that I think religion has very positive aspects: community, belonging, purpose, an answer to what happens after death.

But I'd also say that historically, religion (especially Christianity) was a tool to keep the masses docile and subdued, allowing the church to hold power over hundreds of years but also kept believers somewhat safe, at lest from their own community - commandments like do not kill, steal, or even Jewish customs of not eating specific types of meat. If they had to make up, or embellish things to keep it going, that was a price they were willing to pay.