Could you provide a short list of what you consider, primary doctrines and secondary doctrines?
Well, this would vary amongst the denominations. For example, Anglicans, Lutherans, Methodists, and some Reformed would prefer to abide by
prima Scriptura instead of
sola Scriptura. Sacred Tradition is very important to them, so I will exclude them. They would consider their Book of Discipline, their Book of Concord, their Common Prayer, and their Confessions of Faith as primary. So we are now only dealing with “low” churches.
The ones I think are “low” churches are mainly congregationalists without a bishop (some Presbyterians, most Baptists, Quakers, Brethren, et. al.). Most would say that there are three kinds of beliefs: (1) fundamental beliefs, (2) primary beliefs, and (3) secondary beliefs.
Fundamental beliefs are those beliefs which any child can understand when they listen to the Bible stories. For example, God loves them. God sent His son Jesus Christ to die for their sins, etc. etc. One would not even need a teacher for these fundamental beliefs.
Then there are primary beliefs as indicated in their Confessions of Faith (Westminster Catechism, London Baptist Confession, etc.). These beliefs usually include 66 Books of the Bible, Trinity, Incarnation, Atonement, Two Sacraments, and the Return of Christ. I think most of these beliefs require the Nicene Creed which is part of Sacred Tradition, but “low” churches think they can get in from Scripture
certainly. Quakers and other really liberal “low” churches would consider even these as secondary. I think they are more consistent.
The conservative “low” churches’ secondary beliefs would be the end times (premilliennial, amillennial, etc.), the manner of baptism (baptism by immersion vs. sprinkling), the order of salvation, form of church government, nature of the Eucharist (spiritual presence or symbol), the other five sacraments, and a whole lot of others I cannot recall.
Hope this helps,
Francis