The ancient Greeks believed in an afterlife called Elysium, which was where those chosen by the gods – the righteous and heroic – would spend eternity in happiness and enjoyment. This was distinct from Hades, where evil people were destined to suffer after death. Similarly, the Jews believed in heaven, a place where God dwelled and the righteous spent eternity with him after death. Hell was the opposite, where the evil were forever tortured apart from God. However, ouranos, the Greek word for “heaven” could also mean a number of other things within the context of the Greek-speaking Jewish society of Jesus’ day.
The “first heaven” was understood to be simply the space that surrounded every creature on earth. It was synonymous with the atmosphere. After Jesus was baptized, God spoke as “a voice out of the sky”, but the word recorded in Greek is actually ouranos, heaven.
The “second heaven” was everything else in the universe beyond the earth – the space containing planets, stars, and galaxies far away. When Jesus talked about the end times, he said “the stars will fall from heaven”, that is, outer space.
The “third heaven” was the world beyond the physical realm. It was the spiritual realm of angels and demons, where non-physical beings like God himself were clearly seen and heard. This third heaven was what Paul had a vision of when he was “caught up into paradise and heard inexpressible words” (2 Corinthians 12:4). It wasn’t necessarily related to a physical space, but another dimension of reality, a place “beyond the veil” so to speak.
Thus, heaven could mean a number of different things in the Bible, depending on the context. Indeed, sometimes all meanings were intended, as when Jesus instructed his disciples to address God as “our Father in the heavens”. The word he used was the plural form, encompassing all of the heavens from the atmosphere to the rest of the universe to the heavenly realm where God is seen.