अहिंसापरमो धर्मः, धर्म हिंसा तथीवच। अहिंसा परमा धर्मो, हिंसातथैव च॥

This shloka means “Non-violence is the highest duty, even higher than the duty of practicing religion. Non-violence is the ultimate religion, just as violence is the ultimate irreligion.”

The origins of this shloka can be traced back to Hindu scriptures such as the Mahabharata and the Manusmriti. Mahatma Gandhi was the one who popularized this shloka and used it as a guiding principle for his life and work. He believed that non-violence was the only way to achieve true peace and justice in the world.

Ahimsa Paramo Dharma is a Sanskrit phrase popularized by Mahatma Gandhi, meaning that non-violence is the topmost duty that supersedes all other duties. However, it is important to note that in Sanatana Dharma, Ahimsa is a general dharma that can be superseded with himsa (violence) in order to protect dharma. The statement emphasizes the need for non-violent resistance, even in extreme situations, and its application in every case and matter. Gandhi popularized this phrase and used it as a cornerstone of his philosophy of non-violent resistance. 

However, Gandhi's emphasis on the first line of the shloka alone led to criticism that he misinterpreted the meaning of the phrase. In conclusion, in the extremism of terrorism, this shloka is particularly relevant and emphasizes the need for non-violent resistance and the importance of using violence in the service of dharma.

In the context of the extremism of terrorism, the shloka "Ahimsa Paramo Dharma" holds great significance as a reminder that non-violence is the highest duty. However, it is important to remember the complete shloka, which recognizes that violence can also be necessary in certain situations. Therefore, while non-violence should always be the first resort, it may not always be the only resort.