You must see that what you are doing, that is according to the principle which all other sadhus and devotees do. They have tilaka, and you say, "I have no tilaka." That is not sadhu–marganugamanam [the path of following the sadhus]. They have kanthi. You say, "I can avoid it." That is not sadhu-marganugamanam. So from very beginning, if you disobey, then how you'll make progress? 

Srila Prabhupada — January 27, 1977, Bhubaneswar