CC Ādi 3.61

bhaktira virodhī karma-dharma vā adharma
tāhāra ’kalmaṣa’ nāma, sei mahā-tamaḥ
Word for word: 
bhaktira — to devotional service; virodhī — averse; karma — activity; dharma — religious; vā — or; adharma — irreligious; tāhāra — of that; kalmaṣa — sin; nāma — the name; sei — this; mahā-tamaḥ — great darkness.
Translation: 
The greatest ignorance consists of activities, whether religious or irreligious, that are opposed to devotional service. They are to be known as sins [kalmaṣa].