Then I guess they don't practice true Christianity. The first rule of Christianity is to love God utmost. The second is to love thy neighbor as you love theyself. As Christ said: "Treat the least amongst you as you would treat me."
There are numerous, cases of violence committed by upper caste christians in my state against their lower caste "brethren". Yes, its ironic since both Islam and Christianity seem to stand against racial discrimination, but apparently its only on paper, just like Hinduism.
But I dont think anyone can claim that Christianity is a "solution" for solving the racial/caste inequity problem. Even if someone had brutally imposed Christianity or communism or whatever, on the entire people, caste system would still exist.