So, that in my opinion is what Hindus are up against. The Christian missionaries are nothing if not shrewd. They sail with the opinion winds and have ably made the switch from colonial racism to postcolonial anti-racism, and now they are using this new line with good effect against Hindu society.
Digging up the dirt on "white Christian" history will only evoke a yawn from the Christian conversion apparatus, as that dirt has been dished out already all over the official textbooks and media in Christian countries.
If Hindus want to stop the gains continually made by the Christians in the battle for the souls, there is no alternative to the laborious task of:
(1) informing the world about the more complex and less extreme reality of the Varna system in history and in the present
(2) actually reforming society to the point where caste oppression is only a memory, and ensuring that the world knows about this.
(3) refocusing the Hindu-Christian struggle to its proper doctrinal level, where the defining Christian teachings can be exposed as the unhistorical claims and irrational beliefs that they really are.
Plus, of course, reaching out to the converts who are willing or eager to return to the Hindu fold. These are big and demanding jobs, but they carry a better promise of success than locking yourself in a smug self-assurance of how evil Christians are.