Because all Christians do not agree on doctrine and are not a unified body in one denomination, many atheists reject the gospel. Legitimate questions atheists could ask include: "How do I know what to believe about Jesus if Christians themselves do not agree?" or "Which denomination has the truest form of Christianity and how does one choose the right church?" Admittedly, these are good questions.
At the website Ask the Atheist, schisms that create denominations are explained this way:
"When a religion splits into two denominations, it's called a schism (pronounced 'SKIZZ-um'). People in the same denomination may argue a great deal, but when a particular dispute over religious practice, doctrine or dogma spreads far enough the two factions officially declare each other to be wrong in the eyes of their deity. That moment is when the schism happens, and afterwards the two groups are referred to using different names."
The Atheist goes on to explain that denominations exist because there are "no real Christian theocracies left, and no denomination is able to force dissenters into line the way the Church once could."
An example of divided fellowship is the relationship between Lutherans and Calvinists, two of the world's oldest post-Roman Catholic traditions. At The Gospel Coalition website, Kevin DeYoung, senior pastor at University Reformed Church in East Lansing, Mich., writes about the absence of Lutherans "in the big tent of evangelicalism." DeYoung's evangelicalism (which is primarily Calvinistic) does not encounter many confessional Lutherans. In response, Jonathan Fisk, pastor of St. John Evangelical Lutheran Church, one of the oldest congregations in The Lutheran Church-Missouri Synod, posted a video that has generated nearly 3,000 views in a few weeks. Why? Because, as the atheists point out, there are real, substantial differences between Christians.
Fisk holds that Christians are divided into the four main fellowships: Eastern Orthodox, Roman Catholic, Reformed, and Lutheran. He argues that all denominations are, in the end, connected to one of these four. Each of these fellowships believes that the others are wrong on essential doctrines.
The Atheist understands this:
"If the Christian God exists, He probably would want Christians to unite under a single banner, and Christians of all denominations likely realise this. However, they reason, if the wrong denomination wins out and all Christians embrace the wrong doctrine, then nobody will really be doing God's will at all. Those of each denomination think they've got the right one, and most often decide that Christian unity ultimately isn't worth abandoning the 'true' faith. It's their way or nothing. Of course, this leaves all Christians at a gigantic impasse."
Are the four fellowships at an impasse? Fisk explains that the continuation of divisions in Christianity is not unique because "we're sinful human beings who prefer people like ourselves to anyone who would challenge the status quo, and you find that everywhere." Even the atheist has to admit that there are different kinds of atheists who do not agree about what atheism means. Division reveals something about human nature.
The DeYoung/Fisk conversation raises several questions in my mind. How should Christians respond to the atheist question about division? Will the Gospel Coalition ever have Lutheran speakers at its conferences? Will Lutherans invite Reformed speakers or Catholics to theirs? Does schism undermine the truth of Christianity to nonbelievers? Do those four fellowships constitute different Christianities? Are there beliefs that all Christians, regardless of fellowship, upon which all Christians agree?
I certainly do not have all the answers but the answers matter a great deal. There is much work ahead of the Church, because how these questions are answered bears witness to the truth of the gospel call to a watching world.