Anyone who has read Twain’s writings and orations, especially in the latter years of his life, would know he was no friend of Christianity.
“A God who could make good children as easily as bad, yet preferred to make bad ones; who could have made every one of them happy, yet never made a single happy one; who made them prize their bitter life, yet stingily cut it short; who gave his angels eternal happiness unearned, yet required his other children to earn it; who gave his angels painless lives, yet cursed his other children with biting miseries and maladies of mind and body; who mouths justice, and invented hell — mouths mercy, and invented hell — mouths Golden Rules and forgiveness multiplied by seventy times seven, and invented hell; who mouths morals to other people, and has none himself; who frowns upon crimes, yet commits them all; who created man without invitation, then tries to shuffle the responsibility for man’s acts upon man, instead of honorably placing it where it belongs, upon himself; and finally, with altogether divine obtuseness, invites his poor abused slave to worship him!” — Mark Twain, The Mysterious Stranger
“Most people are bothered by those passages of Scripture they do not understand, but the passages that bother me are those I do understand.” — Mark Twain
“Jesus died to save men — a small thing for an immortal to do, & didn’t save many, anyway; but if he had been damned for the race that would have been an act of a size proper to a god, & would have saved the whole race. However, why should anybody want to save the human race, or damn it either? Does God want its society? Does Satan?” — Mark Twain
That’s OK, though. No true believer would let themselves be swayed by a heathen like Mark Twain anyway. Still, might want to avoid using him to promote your religion in the future.