There exists the deplorable practice today of invoking the words “be in the world, not of the world” in a saintly voice in justification of wallowing in vicious self-love. This excuse comes almost subconsciously, and not surprisingly: it is, more often than not, yet another wise maxim projected onto church-going hedonists to gratify their egos.
What is it to be in the world and not of it? It is to walk wholly in the imitation of Christ, in the examples of the Saints and the Blessed Mother. It is to be a vessel of grace, a person who despises the things of the flesh and desires enmity from the world only after the desire for union with God. I would guess most of us are far from this degree of holiness.
If one drop of the grace of God is lost in the attempt to venture into the world for the conversion of sinners, then it is all for naught: for then you are in need of conversion yourself, and your efforts are fruitless. If you do not have the charity of Christ to successfully lead others to the Word made flesh without giving yourself up to the things of the flesh, they do not dare to say the words “in the world, but not of it” with the example of yourself in mind.
This teaching is not an excuse to live like a heathen, nor is it a commencement to abandon vigor or forfeit virtue in order to try and bring people to the Faith. While the intent to convert others is indeed honorable, your efforts will be much more meritorious if you yourself are much more virtuous.
To be in the world of modern America is to likely lose your soul. The culture of the present age is beyond repair: the sheer degree of paganism, hedonism, nihilism, satanism, and every other horrible -ism present in society is enough to corrupt a person if he should but dip his toe in for a second. To repeat the maxim but live according to the prescribed social norms is comically dissonant, an attitude which is incongruous with true Christian behavior. It is such a practice which only drives away infidels and drags a Christian deeper into mediocrity. And mediocrity kills.
Does the instruction, then, to be in the world not hold today? God forbid! But be a recluse from the culture and hide your face from sin. It is no coincidence that the contemplative religious life is- objectively- the highest vocation and surest way to sanctity. Form your own world, find like-minded people who genuinely practice virtue. Be aware that most every imitation of culture, any sinful similarity between the heathen and the Christian is to be avoided. We always have a duty to care for our own souls before we turn to others’, as the Holy Scripture tells us.