When on the battlefield of Kuruksetra, this is the beginning of Bhagavad Gita,  Arjuna was  initially not prepared to fight. In the early parts of the Bhagavad Gita, one can read of why and the seemingly good reasons he gave Krishna .

Arjuna became bewildered because he had to consider every type of moral and ethical behaviour,  as a good warrior does , a good soldier is not a cold ruthless killer , and certainly will not kill women and children or citizens. Warfare is a tricky business, and many considerations should be made .Arjuna turned to Krishna and submitted himself ,  he asked Krishna what he should do and why it would be the right course of action to fight . Arjuna importantly and  obviously had initial faith that Krishna would give him good advice .

At the point Arjuna turned to Krishna and submitted himself in honesty and with humility Krishna took up the position as Arjuna’s spiritual Guru and thus  chastised Arjuna calling him Mudha , a fool , for thinking he was speaking learned words in giving the reasons why he was not prepared to fight . Krishna began to  point out his lack of real knowledge both materially and spiritually , in terms of what consciousness is , what duty is, and what morality of the highest order is . Spiritual consciousness and its development are always a priority, and Arjuna was only calculating things u to satisfy his own limited interests.

The important point here is that Arjuna initially turns to Krishna with faith and waits and is prepared to hear from Krishna .

After hearing from Krishna, who cleared up all  his misconceptions, Bhagavad Gita makes every clear to everyone, Arjuna intelligently surrendered WITHOUT  RESERVATIONS , and he spoke as follows

Arjuna said: You are the Supreme Personality of Godhead, the ultimate abode, the purest, the Absolute Truth. You are the eternal, transcendental, original person, the unborn, the greatest. All the great sages such as Nārada, Asita, Devala and Vyāsa confirm this truth about You, and now You Yourself are declaring it to me.

This full surrender without reservations is required when it comes to  taking Sri Guru.  who comes in msny forms , both Diksa and Siksa . Sadhu Sastra, after proper surrender and services, can be also consider as non different than Krishna or  Guru . Whether Diksa or Sisksa ,and in particular the highest sense of Siksa of the higher Madhyama or Uttama,  can not be doubted , he can be questioned, but we must be prepared to accept his answers.

It might take time to understand Sri Guru but we must be patient and Krishna will help us , but a bone fide Guru as Krishna was to Arjuna , explains everything logically with reference to authority , such a Uttama Guru can be and should be surrender to without reservation.

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