Why do I believe that we should we become aware of our metaphysical assumptions?

From a strictly metaphysical perspective, I guess that the important thing is to recognize what we are assuming in an "it just is" way, and what is secondarily explained in terms of these assumptions. 

If this is achieved to some extent; I think we can then compare metaphysical "systems" or schemes, and then there is a basis for choosing between them. 

For instance, one person may regard an explanation of freedom/ free-will/ agency as vital to him; but another person may desire that everything he considers important must be as it is, with no contingency, and no possibility of things being otherwise. 

Such personal imperatives will influence the choice of metaphysical assumptions. Or perhaps, when a person becomes explicitly aware of his own current imperatives, he may come to disapprove of them, and may then reject them*.   

Simply to clarify what one actually is assuming - in a clear and explicit way - is itself something very valuable -- maybe essential when it comes to really fundamental matters. 

Personally, I want my primary assumptions to be the kind of thing that is knowable intuitively, by personal revelation - and without having to depend on communications that may be unreliable, from secondary sources that may not be accurate or trustable. 

This has meant that - over time - it has been necessary to reduce the dependence of my core faith not only on church teachings, but also on scripture. I have come to regard both church teachings and scripture as (for what seem very obvious reasons) unsure and unreliable. 

I simply cannot stake everything on the accuracy of scriptural transmission and interpretation, or the integrity of any actual modern institution - whether or not it calls itself a church. 

To generalize, and for a Christian, this means (among other things) "knowing" both God the creator, and also (and more importantly) the person of Jesus Christ for oneself; know them "here and now" as it were - and as the root of everything else.

This is edited from a comment at Francis Berger's blog

*As an example of what I mean: One metaphysical assumption of this kind that I rejected after having become aware and clear about it; was that God our loving Father would create the world such that "the church" (or churches in general - or access to accurate scriptures) was necessary to salvation. This is a very common assumption, even nowadays; but once I had made it explicit, it seemed clearly wrong. A Good and Loving God who desired the salvation of Men would not organize things thus; because the world and its people are far too varied (over time and geographically), and there is far too much that could (and would, and has) go awry in terms of making salvation depend upon any specific worldly entity, its dissemination, and understanding. It seemed obvious that God would make it possible for all of his children to attain salvation in whatever circumstances they found themselves or contrived; and this would need to be done directly - that is, by sufficient and needful unmediated contact: by what is sometimes termed "personal revelation". Since it is Jesus Christ who is essential for each Man's salvation; the attaining of salvation would need to be something primarily decided between Jesus (here and now - not depending on historical records), and each Man in his specific circumstances... Including (importantly) each Man's specific circumstances after biological death, and before the choice of salvation or not.