In Christian historical terms, the name "
gnostic" is used to refer to someone who claims to have "
special" knowledge that one needs to be a Christian.
The word "gnostic" means someone who has special knowledge.
The word "agnostic" means to not know.
The gnostic ideas were not prevalent until later. Think about it. It is hard to claim that one needs special knowledge about Jesus when there were eye witnesses still alive. One would not get very far.
What was prevalent at this time were those who would claim that extra work was needed.
Paul does not appear to be addressing "
gnostics" in chapter 3 of Philippians. It is hard to start a "
gnostic" movement when eyewitnesses are still alive. Any "
gnostic" (false) beliefs were addressed to the leadership in chapters 1 and 2.