But to have this unifying function, creeds or confessions must adequately summarise Biblical doctrine, and church members being convinced of this fact. If church members don't think the creed is Biblical, it won't serve its pastoral function. Therefore, it's more important to teach people from the Bible, and use the creed or confession to summarise the Biblical teaching - which is, after all, the confession's role.
Creeds… are a testimony of the church’s belief to the world; they offer a summation of Christian doctrine for the instruction of the faithful; they form a bulwark against the incursion of error by providing a standard of orthodoxy and a test for office-bearers. In these ways creeds also serve to protect and to foster the bond of Christian fellowship as a unity of faith and doctrine, of mind and conviction, and not merely of organization or sentiment. 
[T]he confession is not co-ordinate with Scripture nor the primary ground of faith. It is derivative and thus subordinate but yet not opposed to Scripture. It merely seeks to set forth what Scripture teaches on various subjects so as to be a suitable bond of union for those agreed as to the teaching of Scripture. 
[S]ubscription [to a creed or confession] is not the answer if one is seeking to create theological unity out of diversity. Rather it is an instrument of enforcement and preservation of existing orthodoxy and consensus... First there must exist a consensus to guard, before one discusses how best to guard it. Because no creed or confession is inspired, it may be changed or restated. If it is unbiblical, it needs to be changed. If it is outdated, it may be restated in language that better communicates with the current generation.
[S]ubscription in the Scottish tradition is to the doctrine of the [Westminster] Confession and not to its words as if they were inspired. A restatement or reformulation of the teaching of the Confession which preserves the doctrine is fully in line with the duty of the church to proclaim the truth to each generation. It also agrees with the practice of the church at an earlier time: when the Westminster Confession replaced the Scots Confession of 1560, it was regarded as ‘in nothing contrary to the received doctrine’ of the Church. 
In all of this, the pastoral purpose of creeds & confessions must be kept in focus. They lead the flock into the green pastures of the Bible, they nourish and strengthen believers in the faith "once for all delivered to the saints" (Jude, verse 3).
 Robert Rayburn. "Biblical and Pastoral Basis for Creeds and Confessions," in The Practice of Confessional Subscription (ed. David W. Hall; Langham: University Press of America, 1995): 21.  Rowland Ward, "Divisions and Unions in Australian Presbyterianism 1823-1901, with Special Reference to the Church's Attitude to its Creed" (Doctoral Thesis, Australian College of Theology, 1994): 13.
 Ligon Duncan III. "Owning the Confession: Subscription in the Scottish Presbyterian Tradition," in The Practice of Confessional Subscription (ed. David W. Hall; Langham: University Press of America, 1995): 87.
 Ward: 13.