The Muṇḍaka Upaniṣad confirms that the Supreme Lord, in whom everything is resting, can be realized only by those who engage constantly in thinking of Him. This constant thinking of Kṛṣṇa is smaraṇam, one of the methods of devotional service. It is only by devotional service to Kṛṣṇa that one can understand his position and get rid of this material body.
In the Vedas the Supreme Lord is accepted as the purest of the pure. One who understands that Kṛṣṇa is the purest of the pure can become purified from all sinful activities. One cannot be disinfected from sinful activities unless he surrenders unto the Supreme Lord. Arjuna's acceptance of Kṛṣṇa as the supreme pure complies with the injunctions of Vedic literature. This is also confirmed by great personalities, of whom Nārada is the chief.
(Bhagavad-Gita----10:12-13----purport).

That is the actual Vedic process, and those who are actually in the Vedic line hear about Kṛṣṇa from authority, and by repeated hearing about Him, Kṛṣṇa becomes dear. As we have several times discussed, Kṛṣṇa is covered by His yoga-māyā potency. He is not to be seen or revealed to anyone and everyone. Only by one to whom He reveals Himself can He be seen. This is confirmed in Vedic literature; for one who is a surrendered soul, the Absolute Truth can actually be understood. The transcendentalist, by continuous Kṛṣṇa consciousness and by devotional service to Kṛṣṇa, can have his spiritual eyes opened and can see Kṛṣṇa by revelation. Such a revelation is not possible even for the demigods; therefore it is difficult even for the demigods to understand Kṛṣṇa, and the advanced demigods are always in hope of seeing Kṛṣṇa in His two-handed form. The conclusion is that although to see the universal form of Kṛṣṇa is very, very difficult and not possible for anyone and everyone, it is still more difficult to understand His personal form as Śyāmasundara.
(Bhagavad-Gita----11:52----purport).

A devotee of Kṛṣṇa is friendly to everyone. Therefore it is said here that he has no enemy (nirvairaḥ). How is this? A devotee situated in Kṛṣṇa consciousness knows that only devotional service to Kṛṣṇa can relieve a person from all the problems of life. He has personal experience of this, and therefore he wants to introduce this system, Kṛṣṇa consciousness, into human society. There are many examples in history of devotees of the Lord who risked their lives for the spreading of God consciousness. The favorite example is Lord Jesus Christ. He was crucified by the nondevotees, but he sacrificed his life for spreading God consciousness. Of course, it would be superficial to understand that he was killed. Similarly, in India also there are many examples, such as Ṭhākura Haridāsa and Prahlāda Mahārāja. Why such risk? Because they wanted to spread Kṛṣṇa consciousness, and it is difficult. A Kṛṣṇa conscious person knows that if a man is suffering it is due to his forgetfulness of his eternal relationship with Kṛṣṇa.
(Bhagavad-Gita----11:55----purport).

In many places the word bhajati is expressed in relationship with the service of the Supreme Lord. If a person is engaged in full Kṛṣṇa consciousness, in the devotional service of the Lord, it is to be understood that he has understood all the Vedic knowledge. In the Vaiṣṇava paramparā it is said that if one is engaged in the devotional service of Kṛṣṇa, then there is no need for any other spiritual process for understanding the Supreme Absolute Truth. He has already come to the point, because he is engaged in the devotional service of the Lord. He has ended all preliminary processes of understanding. But if anyone, after speculating for hundreds of thousands of lives, does not come to the point that Kṛṣṇa is the Supreme Personality of Godhead and that one has to surrender there, all his speculation for so many years and lives is a useless waste of time.
(Bhagavad-Gita----15:19----purport).

One should be attracted by the beautiful vision of Kṛṣṇa. His name is Kṛṣṇa because He is all-attractive. One who becomes attracted by the beautiful, all-powerful, omnipotent vision of Kṛṣṇa is fortunate. There are different kinds of transcendentalists—some of them are attached to the impersonal Brahman vision, some of them are attracted by the Supersoul feature, etc., but one who is attracted to the personal feature of the Supreme Personality of Godhead, and, above all, one who is attracted by the Supreme Personality of Godhead as Kṛṣṇa Himself, is the most perfect transcendentalist. In other words, devotional service to Kṛṣṇa, in full consciousness, is the most confidential part of knowledge, and this is the essence of the whole Bhagavad-gītā. Karma-yogīs, empiric philosophers, mystics and devotees are all called transcendentalists, but one who is a pure devotee is the best of all. The particular words used here, mā śucaḥ, "Don't fear, don't hesitate, don't worry," are very significant. One may be perplexed as to how one can give up all kinds of religious forms and simply surrender unto Kṛṣṇa, but such worry is useless.
(Bhagavad-Gita----18:66----purport).