Doctrinal Sanctification

In considering the sine qua non i.e. without which it could not be, of the "historic christian faith", i am wondering how much of "the faith" a person has to understand in order to be considered "in the faith"? In other words, i am wanting to know how many, or which of the tenants does it take to be associated in the church, and how much of what i will call "doctrinal sanctification" can play a role in shaping a person's correct understanding of those tenants post-christian conversion/experience. Roughly stated: it seems to me that the sanctification of a person can deal with attitudes that are unchristlike as well as doctrines that are unchristlike. While not affirming error, but desiring truth (especially in this post): how much did your understanding of Christ and the cross (associated terms and doctrines) did it take for you to truly be saved, and how much has your understanding of Christ and the cross morphed since then? My hunch is that some people will naturally propose the tenant: "justification by faith", that said (and if i'm right) how much of that teaching must one understand? Again, does someone simply believe in the value of Christ going to the cross for their sins or is the implication that, that person has to comprehend the matrix of the phrase "justification by faith"? I realize my post is rough around the edges in cognancy but hopefully it makes a little sense... :-)