Debating Atheism - quotes

But sometimes a preacher will avoid a fight if he sees that the 
challenger simply wants to argue for the sake of argument. Rupa 
Gosvami once declined to debate a rascal who came to defeat him, but 
then Rupa's nephew, Jiva Gosvami, took up the challenge. So a devotee 
may or may not choose to meet the challenges of the atheists and 
voidists, depending on the circumstances, but in any case he knows 
that debate and challenge do not lead to a true understanding of God. 
Narada Bhakti Sutra 5.74 p.

Some evenings Prabhupada would speak or arrange debates, although 
Kirtanananda was constantly cautioning. When Prabhupada wanted to 
speak, it was impossible for any of his disciples to stop him. 
Sometimes he would ask Kirtanananda to debate with one of the visiting 
devotees. One devotee would argue for the impersonalist's or atheist's 
position, and the other would argue for the Krsna conscious position. 
Prabhupada would judge. But no sooner would the argument begin than 
Prabhupada would interrupt, take the position of the devotee, and 
defeat the atheistic or impersonalistic argument. The devotees loved 
it. Prabhupada was unable to confine himself either to the role of a 
silent judge or to that of a recuperating patient. "Why do we 
concentrate on the impersonalists?" Kirtanananda asked. "Why do we 
attack them so much? Why don't we concentrate our attack on the 
atheists?" "You say that because you are an impersonalist," Prabhupada 
answered angrily. SDG: SPL 3.26

Commentary: Sahajiyas reject the study of all Vaisnava literatures in 
the claim that they are mundane and speculative. It is sentimental for 
a devotee to think that he should not argue philosophically. No 
devotee should renounce philosophical debate out of laziness or 
sentimentality. Rather, every preacher must equip himself to defeat 
opposing philosophies by reading Prabhupada's books. He should then 
enter the atheistic atmosphere created by materialistic scientists and 
others and deliver the Vaisnava conclusion, or siddhanta, on every 
issue of controversy. Such issues include the origin of life, the 
existence of God, whether God is personal or impersonal, God's 
identity, and the question of the divine origin of the scriptures. 
SDG: Reading Reform, Quotes 8

Vishnujana Swami: Yes, you can always challenge them, but you are not 
to discuss with them. In other words, you don't debate with them, you 
just challenge them that, "We say 'Thou shalt not kill' means 'Thou 
shalt not kill any living beings.' And whatever one has to kill for 
maintaining this body, that should be offered, according to the rules 
of scripture, to God." That's all. Then when they want to debate, you 
say, "No, we are not debating with atheists."
Vishnujana Swami Nectar - 27 Talks and Lectures, NOD 7 - Los Angeles, 
May 8, 1973

Seminars:
Meditation (7 hrs.)
(Continuation)
Public Lecturing (10 hrs.)
(Continuation)
Debating (5  hrs.)

Debating with atheists and followers of impersonal philosophies. For 
purposes of debate, student will assume role of antagonist. After 2.5 
years of public lecturing, students become very familiar with 
atheistic and impersonal arguments.) Hare Krishna Handbook 7b