Lecture on Bhagavad-gītā 2.20–25, October 14, 1968, Seattle

So Kṛṣṇa consciousness movement means that we have
to train our senses to satisfy Kṛṣṇa. That’s all. So long in
other, previous, many, many thousands and millions of
lives, we have simply tried to satisfy our senses, personal
senses. Let this life be dedicated for satisfying Kṛṣṇa’s
senses. That is Kṛṣṇa consciousness. One life. We have –
several lives we have tried to satisfy our personal senses.
Let this life, at least one life, let me try, what happens.

Śrīmad-Bhāgavatam 2.9.36, purport

Therefore there is no need to seek properly qualified
candidates for discharging devotional service to the Lord.
Let them be either well-behaved or ill trained, let them be
either learned or fools, let them be either grossly attached
or in the renounced order of life, let them be liberated
souls or desirous of salvation, let them be inexpert in the
discharge of devotional service or expert in the same –
all of them can be elevated to the supreme position by
discharging devotional service under the proper guidance.

Letter to Madhudviṣa Dāsa, September 7, 1969

Sincere devotional service in even one lifetime
is sufficient to make one eligible to return to the
Vaikuntha world permanently. Krishna Consciousness
has got this power. So stick to this path as you are
now doing, and as your sincerity and determination
increase more and more, Krishna will surely be
pleased to bestow all of His blessings upon you.

Śrīmad-Bhāgavatam 4.21.33, purport

Anyone can become successful in devotional service
provided he displays no duplicity. It is explained
here that one must be very frank and open-minded
(amāyinaḥ). To be situated in a lower status of life
is not a disqualification for success in devotional
service. The only qualification is that whether one
is a brāhmaṇa, kṣatriya, vaiśya or śūdra, he must
be open, frank and free from reservations.

Śrīmad-Bhāgavatam 2.9.8, purport

Following the order of the bona fide spiritual
master is the only duty of the disciple, and this
completely faithful execution of the order of the
bona fide spiritual master is the secret of success.

Caitanya-caritāmṛta, Antya-līlā 1.32, purport

By rendering a little service, even by eating
prasādam, what to speak of chanting and
dancing, everyone can be promoted to
Vaikuṇṭhaloka. It is therefore requested that
all our devotees in the ISKCON community
become pure Vaiṣṇavas, so that by their mercy
all the people of the world will be transferred to
Vaikuṇṭhaloka, even without their knowledge.