Sad-dharma, or duty performed for going back to Godhead and thus becoming His unalloyed devotee, is the only pious activity; all others may pretend to be pious, but actually they are not. It is for this reason only that the Lord advises in the Bhagavad-gītā that one give up all so-called religious activities and completely engage in the devotional service of the Lord to become free from all anxieties due to the dangerous life of material existence.
-Shrimad Bhagavatam Canto 2 Chapter 10 Verse 4, Translation and Purport

अन्तवन्त इमे देहा नित्यस्योक्ताः शरीरिणः ।
अनाशिनोऽप्रमेयस्य तस्माद्युध्यस्व भारत ॥ १८ ॥
The material body of the indestructible, immeasurable and eternal living entity is sure to come to an end; therefore, fight, O descendant of Bharata.
-BG 2.18