Whose mind is on earthly things. Philippians 3.19
When the Scriptures introduce our enemy, the devil, the first thing it says of him is that he is subtle. He does not come to us as an angel of darkness but as an "angel of light," his ministers masquerading as "ministers of righteousness." So, when we read the warnings of the apostles, we must keep in mind that these are given so that we may avoid the subtle traps of Satan. We hardly need any warning about the obvious.
Paul warned the Philippians about those who are earthly-minded. Evidently, there had arisen within the churches those who lived as enemies of the cross of Christ. Their god was their "stomach" (that is, their natural appetites), they gloried in the very things about which they should be ashamed, and evidently, they were able to do this even as the church had no clue that they were not really believers. But we know they were not really believers for "their destiny is destruction," and none of God's elect have that destiny.
So, we are led to ask, "What sort of earthly-mindedness might be so subtle as to deceive God's people?" Here is one: Many have been deceived by the Satanic, "gain is godliness," theme (1 Timothy 6.5). The word translated "gain" actually means "a way to make gain." That is, these people acted godly for a living. By their pious bearing or conduct they insinuated themselves into the churches as leaders so as to become paid ministers. Or, more subtle yet, they acted especially pious so as to gain the respect of the people, enabling them to conduct business with them. And maybe the most subtle of all, they put on extravagant piety in the hope of impressing God so that He might reward their piety with earthly gain.
I believe it is safe to say that anyone whose godliness or piety can be spotted at twenty yard's distance is likely earthly-minded! True godliness is an inward disposition of the heart, not an outward display of religious conduct.
This godliness as a means of gain was most clearly manifested in the religious leaders of our Lord's day. They were easily identifiable by the sort of clothes they wore, their visible displays of humility, and their apparent zeal for the things of God. The common man lived in awe of them. Yet, when the only truly righteous man appeared, these earthly minded "godliness-as-a-means-of-gain" people were filled with rage. These are the men who rejected Christ and loved darkness rather than light for their deeds were evil (John 1.12, 3.19). So long as they lived in the shadowy revelation of the law, they were able to hide in the dark corners of their hypocritical "godliness." But when the full blaze of divine light came in the Person of the Lord Jesus, they were outed for the evil men they were. It became obvious that their religion was an act, that their righteousness in which they gloried was nothing more than "filthy-rag" righteousness of which they ought to be ashamed.
How can the church of God protect itself from the infiltration of such people? It is quite simple – by immersing itself in the preaching of Him who is the light, by having the same determination as Paul: to know and preach nothing other than Christ and Him crucified and to boast in nothing other than the cross of the Lord Jesus Christ (1 Corinthians 2.2; Galatians 6,14). The moment an individual or a church turns its eyes from what cannot be seen to what can be seen - the moment it begins to focus its attention on outward righteousness and godliness, the moment it becomes enamored of outward displays of piety, the moment it turns its eyes from Calvary to Sinai – at that moment it starts down a path of earthly-mindedness that will produce all manner of shameful conduct as the enemies of the cross gain a standing among them and hide the light of the truth in order that they may appear righteous in the shadows.
God spare His saints and His churches from such deceptive earthly-mindedness!