My dad passed away some years ago. Strangely enough, just about everyone in the immediate family, including me, have had dreams about him since. And some of these dreams basically amount to him telling us he's okay and that he's in heaven.
My trying to be open-minded, including on a spiritual level, affords me to consider that possibility that there might be something more to the dreams. Perhaps he did try to give a message?
This message haunts me too, though. I see heaven as perhaps being for Christians. I'm not a Christian. I don't want to be a Christian.
So it seems the odds are slim that I will ever see my dad again some day. And I wish I knew how to reassure myself about it, that despite of that, it may be okay.
But I'm also torn on a philosophical level because my dad while on Earth would want me to choose my own path, no matter what.
So it's like tough love. Choosing what your dad would want for you, for you, but not choosing what your dad might want for him.
Like others said, it seems like there are other religions who claim heaven, one difference with Christianity however is that Christianity is the "inventor" of heaven so to speak, although there are indications of resurrection in old testament although Jews don't believe in eternal live AFAIK.
Regarding your dreams the bible does say a lot about dreams, dreams (not always) can be message from God, not necessarily to one who is believer of God. (like yourself)
For example in the book of Genesis Pharaoh who was not Jew (believer in Yahweh) and likely not believer at all had dreams and Joseph (Jewish) out of many dream interpretators was the only one able to explain his dreams and that become true and he was rewarded for that.
If you wonder why would God give dreams to Pharaoh who wasn't believer in Yahweh, here is what Joseph said about interpretation of dreams:
Genesis 40:8 which seems to indicate that for valid interpretation God is required.
For example Prophet Daniel (like Joseph) had the ability to interpret dreams: Daniel 1:17
What I'm trying to say here is that for valid interpretation of dream you need someone who is gifted by God's spirit rather than resorting to someone who does it by the book such as dream book, this certainly won't work.
I know such people exist, a friar who was my teacher was able to interpret dreams and all of his interpretation become true.
The bible however says nothing about (passed away or a live) people who may be initiators (instead of God) of some ones dreams, no such thing.
But there is other biblical explanation if you're sure that dreams were from your father rather than from God:
In Matthew 2:13 the angel of the Lord was the initiator of dreams rather than God, however in these dreams there was no need for interpretation.
The point here is "the angel", according to other passages from the bible people have their angel guardian and these may appear, ex in
Acts 12:15 they thought Peter's angel come instead of Peter.
Therefore as you indicate based on dreams of your family you are certain that dreams are not false because several people had dreams about your father, therefore if those dreams are not from God then they must
from your father's angel, but not from your father directly since that can't be scripturally validated, hence why there is saying that passed away people can't communicate back.
See also
Job 33:14-17 on why passed away people may not be able to directly be initiators of dreams.
This message haunts me too, though. I see heaven as perhaps being for Christians. I'm not a Christian. I don't want to be a Christian.
You should better ask yourself one other question, if your father was not Christian or not believer at all then how is it possible that he may end up in heaven?
Well there is biblical explanation for that too, because people may go to heaven regardless of their atheist position but under some circumstances.