Yes, in the Bhagavad-gita there are encouragements for violence. That is undeniable. But one have to consider also the following points to see everything in context.

1. All the reasons that lead to the decision to get into war as described in the Mahabharata.
2. Krishna's instructions to fight were very personal to Arjuna who was a soldier.
a. One could fight nowadays only if personally instructed by God, Krishna.
b. Using only the scripture like the Bhagavad-gita as a reason to fight would be completely wrong.
3. With the advancement of the age of spiritual degradation there are more and more people who are violent and angry on all religions. If religious people would like to kill all of them that would mean more than 20% of the world's population would have to be killed. That is not practical nor good.
a. The human form of life is considered very valuable for attainment of enlightenment and self-realization. The true followers of the Bhagavad-gita know this and so they would not kill anybody but rather try to teach the science of yoga and self-realization as explained in the Gita.
b. With the advent of Caitanya Mahaprabhu the above point is even more emphasized. "Help others to attain love of God rather than kill them because they are irreligious."

For the end one remark. There are studies published on the internet that explain how the Bible is more violence encouraging than the Koran. So the question could be, why not ban the Bible and the Koran as well? But no scriptures have to be banned if violent statement are understood in context of time place and circumstances and the above points mentioned.

Seeing the ultimate goal of Bhagavad gita, the development of all good spiritual qualities and the attainment of spiritual perfection in human life-form, the attempt of those who desire to ban the Gita is ridiculous. Obviously motivated with pride, desire for control and prestige they are not interested in such perfection. May Lord Krishna enlighten them so that they understand: THEY ARE DOING SOMETHING REALLY WRONG.

#426: -

I fully agree whith this. Thank you.