Philippians 3:2 - A motley crew...

"Be watching [out for] the dogs, be watching [out for] the evil workers, be watching [out for] the false circumcision..." 

-A motley crew, this.  ‘The dogs’ here are not the domesticated divas of the modern western home.  The imagery is bands of vicous unchecked canines who roamed the streets of the oriental world (cf Psalm 22.16, Psalm 59.6) - in this sense Paul is specifically referring to Judaizers, those nominal converts to Christianity who insisted that entrance to Christ’s kingdom could only be gained thru strict Judaism (cf Acts 15.1).  Thus these were evil workers indeed.  ’False circumcision’ is katatomé.  Only used here in the NT, it means a cutting towards, as opposed to peritomé, meaning a cutting around and usually translated as 'circumcision'.  Strict Judaism maintained that to be a good Jew, one who in man’s eyes was good in God’s eyes, one needed to be circumcised, and then keep the Law of Moses (act 15.5).  And better by far if you were a bonafide descendant of Abraham, Isaac and Jacob, a son or daughter of Israel.  In the beginning circumcision was more of a cultural delineator, in that it marked out who were God’s chosen people.  But after Moses (and ultimately) the covenant of circumcision devolved into a system of works, and it tapped in to fallen man’s instinctive impulse to try and work his way into a right standing with his Creator.  Like the Judaizers, there have always been those who will devise or distort religious systems which purport to be paths towards achieving or maintaining right standing with God, but in the end they are false and misleading approaches which steer a person astray from true righteousness, that which is attained by simple faith in and devotion to Christ (2Corinthians 11.3).  Paul gives strenuous warnings to watch out for these people (cf Galatians 1.8-9, Titus 1.10), and he repeats himself three times here just to emphasize that point.  Those who follow Jesus need to be on the lookout against anyone who would somehow be advocating that we need to DO something, that there is ANYTHING we can do that can earn God’s love and acceptance.  There is no good work we can perform which will do that (Galatians 2.16, Ephesians 2.8-9, Romans 3.20, Romans 3.28, Romans 4.6) - salvation and forgiveness and right standing with God are a free gift bestowed entirely by grace through faith.  God went to great lengths to reinforce this truth to the early Church (cf Acts 15.7-11, all of Acts 10.1-11.17, esp Acts 10.44-47) - it is not about who you are or where you are or what you do - and since our instinctive impulse IS to try and earn His favor, we must be extra vigilant not to get caught up in any system of works and to not let anyone at all influence us in that direction.