उपासत उपास्तापि नार्थदा पुरुषद्विषाम् ॥ ४० ॥
tataḥ — thereafter; arcāyām — the Deity; harim — who is the Supreme Personality of Godhead (the form of the Lord being identical with the Lord); kecit — someone; saṁśraddhāya — with great faith; saparyayā — and with the required paraphernalia; upāsate — worships; upāstā api — although worshiping the Deity (with faith and regularity); na — not; artha-dā — beneficial; puruṣa-dviṣām — for those who are envious of Lord Viṣṇu and His devotees.
Sometimes a neophyte devotee offers all the paraphernalia for worshiping the Lord, and he factually worships the Lord as the Deity, but because he is envious of the authorized devotees of Lord Viṣṇu, the Lord is never satisfied with his devotional service.
Deity worship is especially meant for purifying the neophyte devotees. Actually, however, preaching is more important. In Bhagavad-gītā (18.69) it is said, na ca tasmān manuṣyeṣu kaścin me priya-kṛttamaḥ: if one wants to be recognized by the Supreme Personality of Godhead, he must preach the glories of the Lord. One who worships the Deity must therefore be extremely respectful to preachers; otherwise simply worshiping the Deity will keep one in the lower stage of devotion.