Where is the scriptual mandate prohibiting them from being ordained as ministers?
can see where God would not allow a woman to be HEAD/CHIEF Pastor of a local church, as the man is to represent the head of the Body BUT
Why do we allow Women to teach SS classes, be Missionaries etc but not be assistant pastors?
What SS classes do they teach, well that of course depends on the lpcal pastor in many cases. I believe women are instructed to teach women and children but not men. Paul a woman is not to teach men nor to usurp the authority from a man.
1 Tim. 2: 9 In like manner also, that women adorn themselves in modest apparel, with shamefacedness and sobriety; not with broided hair, or gold, or pearls, or costly array;
10But (which becometh women professing godliness) with good works.
11Let the woman learn in silence with all subjection.
12But I suffer not a woman to teach, nor to usurp authority over the man, but to be in silence.
13For Adam was first formed, then Eve.
14And Adam was not deceived, but the woman being deceived was in the transgression.
Quite clear women are not to teach men. Nor pastor men. To od so goes against the order of creation Adam was formed first and therefore is the head of the family and should be the head of the church. The teaching of course of men is in scriptural things. Since this deals with teaching scripturally it does not apply to music director, or teaching children in sunday school. Paul's admonishion was not to teach men nor have authority over them in scriptural matters. Even as a associate pastor she would be in authority over a man.