If only it were indeed so pure in its body.
That Creed relies on philosophical terminology—such as "substance," "essence," and "person"—terms that don't appear in the Bible or its original languages apart from perhaps some of the more modern versions that are known to be replete with errors.
While the Bible speaks of the Father, Son, and Holy Spirit, the rigidity in the use of metaphysical definitions in the Creed to describe the Trinity are developments known to have originated and thus built upon later, Greek philosophy rather than direct, biblical revelations. You Gentiles seem to have a fixation on such alterations to the wondrous languages from which the Bible was translated. From this Greek-infected perspective upon which the creed was built, its creators attempted to define a mystery using human logic and terminology that the biblical authors were NOT inspired by the Lord to write. The sheer vanity of including such metaphysical concepts and terms is mostly descriptive of Eastern Mysticism's bent upon spiritual things. That's problematic in my mind.
Another point that I find contention with is the Creed's use of exclusive and absolute language where the scriptures are not so concrete in the same direction. For example, the Athanasian Creed explicitly states that whoever doesn't hold the Catholic faith "whole and undefiled" is condemned to "everlasting damnation," thus standing upon a works-based salvational grounding the Bible doesn't uphold for us today under the Gospel of Grace.
This legalistic approach to salvation, based squarely on the precise, intellectual assent to a complex theological formula, isn't found to have been inspired by what you Gentiles call the New Testament. The formers of that creed point to biblical themes of faith, grace, and the simplicity of the Gospel as being at odds with a requirement to master the nuanced distinctions of Trinitarian metaphysics to avoid hell. That isn't at all what either Christ taught, the twelve nor Paul, even though the Kingdom Gospel is somewhat more works oriented in the arena of perseverance as am ongoing demonstration of one's faith.
That Creed also oversimplifies or misrepresents the relationship between the persons of the Trinity contrary to how they're described in the Bible. While the Creed emphasizes a strict equality and co-eternity, certain passages suggest a functional subordination of the Son to the Father (e.g., John 14:28, "The Father is greater than I"). They contend that the Creed's insistence on absolute equality ignores the relational dynamics presented in the Gospels, therefore I don't see that creed as absolutely representative of the Bible it claims to represent.
MM
No this is vastly incorrect. Legalism would be I have to tell you you have to follow the Law to be saved in which case it's probably too late for you and basically the whole world anyways. The Athanasian Creed is the essential Christian statement of faith and it states you have to have faith in God to be saved, furthermore anyone that doesn't have faith in God is certainly going to be damned to hellfire. This is the bookends of the Creed, and it is the central message of the Bible. Thus if one does not affirm the Athanasian Creed they do not believe the Bible fully, they probably have not read the full Bible, they do not really believe in God and Jesus and what the Bible teaches and promises. Thus as a tool for the discernment of spirits; and a way easy way to force a revelation of the true Christians from fake Christians, and even a way to gauge somewhat their levels of faith and gifts; you just ask them to affirm the Athanasian Creed. It is better even to do it line by line, as where they disagree, that's where their demons, heresies, or their pagan religions are at, and thus you can lock in and start kicking the devils around in their minds until the lies are loosened up enough, and they can pull the splinters out of their own eyes and then have power to do the same for others once they convert to the only true religion of Christianity which faith one must fully understand and believe to be saved, praise Jesus.