Theological bias exists in every Bible translation to some degree. In many cases, sad to say it is more than a translation tool but it has been done with a theological agenda. For example, when you translate John 8:58 "Before Abraham was I AM," you are going beyond the role of translator and dipping your toe into the world of the interpreter. There are other cases when translations have rendered highly theological charged verses correctly even though it went against their theology. It is not the goal of the translator to tweak the theological scales to strengthen the defense of a particular theological view regardless of that doctrinal position. Translate God's Word accurately and faithfully and if it strengthens the doctrinal view, fine, if not, fine.
Theological bias has a negative connotation as something to be avoided, and in general, I think it is. But I do not think it would be realistic to argue that Bible translation can be done without theological bias. It is not simply a matter of whether the translator has a theological agenda or not; there are passages in which all the choices of wording necessarily reflect theological positions. Furthermore, if we are going to be completely objective, even orthodoxy is a bias. That is, it is by definition an opinion that inclines or prejudices the translator toward a particular choice of wording when his choices all have theological implications.
“Functional” equivalence as a philosophy assumes that it is possible to create a translation with the exact same meaning as the OL text, without matching the grammatical forms found in the original or using words that match the meanings of the OL words, as established or recommended by lexical research. Of course, it also assumes that a translation done as a formal equivalent differs from a functional equivalent to such an extent as to be contrasted with it. In other words, two such translations will belong to these two separate categories, and there is a dichotomy between them.