According to mythological thinking, God has his domicile in heaven... The meaning is quite clear. In a crude manner it expresses the idea that God is beyond the world, that He is transcendent. The thinking which is not yet capable of forming the abstract idea of transcendence expresses its intention in the category of space; the transcendent God is imagined as being at an immense spacial distance, far above the world.
Rudolf Bultmann, Jesus Christ and Mythology
A false dilemma is a type of informal fallacy in which something is falsely claimed to be an “either/or” situation, when in fact there is at least one additional option. A really good example is this statement[1]:
“I don't believe in a bearded old man in the sky, so I guess I am an atheist.”
whomever
It's imperative for any 21st century adult who wants to believe in God to move away from the notion of the bearded old man in the sky. If you understand that God is transcendent and therefore beyond words, you can begin to understand why there is so much mythological language used when discussing the experience of God. People use language to communicate, and yet language – as a social construct – can only contain signs and symbols that represent collective experience.
So, we end up with such ideas as God being a “bearded old man up in the sky” – a father figure. This makes sense if the source is from a patriarchal society where the oldest male is always the one in charge. (You may note that I avoid as much as possible using any pronouns when I refer to God.)
What other choice is there? Of course, silence is an option. Many of the church fathers and mothers chose silence, embodying Wittgenstein's famous admonition that “whereof one cannot speak, thereof one must be silent.” However, this can also be seen to be a somewhat selfish approach, like finding candy and hiding it in your room so you don't have to share. It is the age-old conundrum of the mystic.
The next time someone laughs at you for believing in “some bearded old man in the sky” I suggest that you “shake the dust from your feet” (Matthew 10:14) and move on.
[1] This might also be an example of a “straw man” argument.