What was the main reason for the split in the Indian National Congress at Surat in 1907?

The main reason for the split in the Indian National Congress at Surat in 1907 was the growing ideological divide between the Moderates and the Extremists. The Extremists, led by figures like Bal Gangadhar Tilak, Lala Lajpat Rai, and Bipin Chandra Pal, believed that the Moderates' methods of prayer, petition, and protest were ineffective in achieving Swaraj. They advocated for more assertive methods like Swadeshi, Boycott, and National Education, and had lost faith in the Moderates' ability or willingness to challenge British rule effectively. This fundamental difference in approach and strategy led to the irreconcilable split, not the introduction of communalism, the foundation of the Muslim League (which was a separate development), or Aurobindo Ghosh's election.