[Aknaton]

Heaven actually has other heavens in it; more like heavenly dimensions or realms. When we are in Christ we are allowed to grow higher and higher in these realms.

However, heaven is not accessible to human beings and they either need God's special permission, have the keys to the gate of heaven or enter on account of someone who has those keys.

One sort of has a portal that starts from earth and bypasses other earthly realms and right to heaven. You can rise up to heaven and chat with Angels, Saints and other heavenly creatures, and they too can come down through this portal.

Being spiritual depends on what you mean. You can be spiritual in the sense of being an occultist or a yogi and investigate the inner and outer realms of self and nature or you can be spiritual in terms of your fellowship, cooperation and yielding to God's Spirit and be able to investigate the higher realms heaven through the portal generated by Him.

And then Hell, I've never actually had an experience.