In Christianity and the Social Crisis (1907), Walter Rauschenbusch compared the sin of speculating in land to the sin of slavery. The great theologian of the Social Gospel tried to open his audience's eyes to the sinfulness of land speculation by reminding them that not long ago, Christians had been unaware of the sinfulness of slavery. Before the abolition of slavery, he wrote, “there were millions of genuine Christians, honestly willing to see and do the right thing in other matters, to whom it seemed a preposterous proposition that slavery is incompatible with Christianity.” To these honest believers, slavery was a necessary social institution like the family or the school. Today, he continued, most Christians, despite their genuine faith, do not realize “that it is a crying wrong to hold land idle for speculation in cities where men's lungs are rotting away … few who realize that it is a flat denial of Christianity to take advantage of the needs of your fellow man to buy his labor cheaply or sell him your goods dearly.” Christians were blind to the evils of industrial society just as they had been blind to the evils of slavery. Both slavery and land speculation were social sins, morally deficient practices that were so deeply embedded in the economic and social structure that they seemed to be “a necessary and inevitable part of the structure of society.” Social sins were different than individual sins. “Genuine Christians” did not tolerate individual sins like drunkenness, adultery, or murder, but they had tolerated slavery.