An ācārya who comes for the service of the Lord cannot be expected to conform to a stereotype, for he must find the ways and means by which Kṛṣṇa consciousness may be spread. Sometimes jealous persons criticize the Kṛṣṇa consciousness movement because it engages equally both boys and girls in distributing love of Godhead. Not knowing that boys and girls in countries like Europe and America mix very freely, these fools and rascals criticize the boys and girls in Kṛṣṇa consciousness for intermingling. But these rascals should consider that one cannot suddenly change a community’s social customs. However, since both the boys and girls are being trained to become preachers, those girls are not ordinary girls but are as good as their brothers who are preaching Kṛṣṇa consciousness. Therefore, to engage both boys and girls in fully transcendental activities is a policy intended to spread the Kṛṣṇa consciousness movement. These jealous fools who criticize the intermingling of boys and girls will simply have to be satisfied with their own foolishness because they cannot think of how to spread Kṛṣṇa consciousness by adopting ways and means that are favorable for this purpose. Their stereotyped methods will never help spread Kṛṣṇa consciousness. Therefore, what we are doing is perfect by the grace of Lord Caitanya Mahāprabhu, for it is He who proposed to invent a way to capture those who strayed from Kṛṣṇa consciousness.
Ref >> Srila Prabhupada Vani.