When Fr. Claret defines his missionaries as people ‘on fire’ with love and who ‘spreads the flame’ wherever he goes, he is defining them as people on fire, passionate, moved by a great interior force.
Elsewhere Claret used the comparison of the fire in a steam engine whose power pulls everything with it with the least effort and he also alludes in another place to the role the fire plays in a gun that fires a bullet with enormous force. ‘Love in a man who preaches the Word of God is like fire in a musket. If a man were to throw a bullet with his hands, he would hardly make a dent in anything; but if he takes this same bullet and ignites some gunpowder behind it, it can kill.’ (Aut. 439) He applies this simile to the efficacy produced by the preaching of one who is animated by the fire of love.
Hence the importance of keeping this fire alive through prayer, the Eucharist, devotion to the loving heart of Mary. If it is not so then the missionaries, or all Christians, are changed into mere ‘functionaries’, including in the religious sense. They would be people moved simply by inertia, by routine, by formalities. The Gospel cannot be lived like this nor be transmitted in an effective or convincing way.
The fire of love makes us creative and forceful in the search for all means to pass it on. It also gives us enormous strength to bear difficulties.
Do we feel really passionate for God and our neighbour, moved by love? Has the fire gone out and we are moved only by inertia and routine?