I specifically asked a question which you did not answer and could not answer, and that failure shows the weakness of your claim. When you state that the majority of the Left is Christian, you are making a broad demographic claim that needs both clear definitions and actual data. You provided neither.
“Left” is not a single global category. The Left in Latin America has many religious influences, the Left in Western Europe is mostly secular, the Left in India mixes Marxists with religious pluralists, and in East Asia Christianity is barely present at all. Without naming a region, your claim has no substance.
Even the term Christian covers many groups with very different political leanings. In the United States alone, Catholics, evangelicals and mainline Protestants do not vote the same way. Treating them as one unit is not accurate.
Most available data shows that left leaning groups tend to be more secular, less religiously observant and more religiously diverse. Right leaning groups tend to show higher religiosity in Western contexts. There are exceptions, but exceptions do not overturn the general pattern.
So when I asked which majority you meant, it was not rhetorical. It was a request for the missing information needed to make your claim meaningful. Since you could not specify it, the claim collapses once you try to anchor it to any real population.