All churches have Creeds. Creed, of course, is of the Latin word "Credo", or "I believe". I've said before that the non-denominational utterance "no creed but Christ, no book but the Bible" is itself a creed. Some churches believe that no one set of beliefs can be right; that too is a belief. The PCA has its own little creed. All churches have a set of beliefs, so all churches have Creeds.
Protestants necessarily teach that all statements of belief are valid (i.e., Truthful) only insofar as they agree with the Scriptures. [I will set aside for now the antecedent problem that this belief follows a priori a belief subject to untruthfulness.] If formulations of belief are only valid where they agree with the Bible, then their worth is as a forum for discussion, an opportunity to strive toward the Truths within the Bible.
Consequently, creeds should always be open to debate, handling, picking apart, and modifying. And that means that no one should be bound ever to subscribe to a belief in one system of theology as Truth. No one should be bound ever to submit to a particular form of ecclesial governance. These things can only be right insofar as they agree with the Bible, and whether they agree with the Bible needs to remain open for debate (for the individual's determination). To lock one into a particular fallible articulation of Truth locks one out of considering that that articulation may be inaccurate, which locks one into a belief that it is accurate, which conflicts with the protestant view that nothing but Scripture is infallible. Phew.
So, to the Protestant mind, no vows for church membership or officership should be taken, other than a vow to the Prior of Priors, that the Bible is God's only Authoritative Revelation. And how the Prior of Priors obtained to infallible status is (as I humbly see it) the great logical flaw of the Reformation.