Let us therefore, as many as be perfect, be thus minded: and if in any thing ye be otherwise minded, God shall reveal even this unto you.
Note 7 at Php 3:15: Paul had just said in Php 3:12 that he wasn't already perfect. Here, he spoke of those who are perfect and put himself in that number. The answer to this apparent paradox lies in the meaning of the word "perfect." As stated in note 2 at Php 3:12, "perfect" can mean spiritually mature, or it can mean "without defect or blemish" (American Heritage Dictionary). In Php 3:12, Paul used the word "perfect" to say that he wasn't flawless or without defect. In this verse, Paul was speaking of being spiritually mature, which he was. The New King James Version and the New International Version translate this verse by substituting the word "mature" for the King James Version's "perfect." The Amplified Bible says "spiritually mature and full-grown."
Note 8 at Php 3:15: The "mind" that Paul admonished us to have was the single-mindedness he described in Php 3:13 (see note 4 at that verse).
Note 9 at Php 3:15: This is a great promise! One of the concerns of many of us Christians is "How can I know I'm thinking and acting properly?" This promise gives the answer. If we seek the Lord with pure hearts and singleness of purpose as Paul described in these verses, then the Lord has obligated Himself to show us anything that needs to change. In other words, all we have to do is keep focused on the Lord with pure hearts, and the Lord promised that He will show us any error. The only people who need to fear that they might be deceived are those who are not seeking the Lord with pure and single-minded hearts.