The framers of the profession claim to be "confessionally bound to the Three Forms of Unity or the Westminster Confession of Faith" (p. 1). Such of course mean nothing if indeed what they teach goes against the Reformed standards.
The first section starts with "Our triune God", as follows:
We affirm that the triune God is the archetype of all covenantal relations. All faithful theology and life is conducted in union with and imitation of the way God eternally is, and so we seek to understand all that the Bible teaches—on covenant, on law, on gospel, on predestination, on sacraments, on the Church—in the light of an explicit Trinitarian understanding.
Immediately, we can see one major problem with this statement. Where in Scripture is God stated to be the "archetype of all covenantal relations"? We are only told that all members of the Trinity are involved in activities such as election, redemption etc. But works are different from relations.
One problem with the statement portrayed here is the archetypal/ ectypal distinction. Since God is three persons in one essence, can we even describe God's intra-trinitarian relationship archetypally? Since we cannot do so, what warrant do we have to even think we can describe it in such a way that we can use it as an archetypal template for relations?
A second related problem is the denial of the creator/ creature distinction. Since when can God's relations be analogous to how God (Creator) relates to Man (creature)? Even if we are talking about interpersonal relations between men, how can relations within the infinite transcendent Creator be considered as qualitatively similar to relations between creatures?
Biblically, the major problem is that the concept is not derived from Scripture but instead contradicts it. We are not left in the dark how God has related to Adam, Noah, Abraham and humanity in general, and these scenarios in the Bible bear no resemblance to the intra-trinitarian relations that God has revealed to us ectypally. God punished Adam for his original sin with death because Adam violated the creation covenant. Is anyone willing to suggest any analogue God's relation to Adam has with God's intra-trinitarian relationship? The thought of it is blasphemous!
We can thus see that the Joint FV Profession at its beginning is already unbiblical. Of course, it can be argued that this particular statement "does not contradict the Reformed standards", for which Reformer could have imagined such blasphemous nonsense? Who could have thought that humans are to try to emulate God in his essence, in who He is?