Easy, you use sound hermeneutics to form your theology. It helps to look at where the church has historically stood on the doctrines too.
>Is it possible to discern spiritual matters
Not only is it possible, it's so easy a child can do it.
The Bible says Jesus died on the cross, that means Jesus died on the cross.
Of course there are harder doctrines to work out, and we are not promised to know every answer, but as a basic question we can obviously know spiritual things.
<14You (Timothy), however, continue in the things you have learned and become convinced of, knowing from whom you have learned them;
<15 and that from childhood you have known the sacred writings which are able to give you the wisdom that leads to salvation through faith which is in Christ Jesus.
<16 All Scripture is inspired by God and profitable for teaching, for reproof, for correction, for training in righteousness;
<17 that the man of God may be adequate, equipped for every good work. (2 Tim. 3:14-17 NAS)
You say "reject superstition too much", but there's no such thing. All superstition is to be rejected, it is all unbiblical.
Different from superstition is the supernatural reality of the universe. God supernaturally created everything, and we supernaturally deal in spiritual warfare. The alternative is naturalism, which says there is no supernatural, and is incompatible with the Bible.