One of the great positions against Christianity is its claim that there is only one true God. Many religions and philosophies around the world claim this same type of exclusivity. Christians believing there way is the only way, offends many people's beliefs that every man and woman can believe whatever they desire, and pursue whatever religious practices that brings them happiness.
When you think of something "exclusive"- like a country club, a resort, or a breaking news story- you think of "No Visitor" signs, and security guards. It's all about access. Those who have it- have it. Those who don't- don't. Exclusive groups don't let others in, particularly those who NOT like them. That's where Christianity is different.
In the Greco-Roman world of the first century tolerance and openness was the way of the world, yet the society itself was brutal. Women and children were seen as second class citizens with hardly any rights or privileges. The lines between those who belonged and those who didn't were well known to all. We can look at the ministry of Jesus and see the two worlds, one of the "sinners", tax collectors, and prostitutes, and one of the "noble", the pharisees, and leaders of the day. It was in this world however, that Christianity thrived. Unlike the first century world, Christians claimed there was only one God, not many. Their beliefs were MORE "exclusive" than others, but they were more open to others.
Because of the freedom they found, women, children, and the second class, ran to the early Christian Church. There they found rights and freedoms society had never afforded them. The Church flourished and grew exponentially because of its openness to others.
Yes. Christianity, orthodox, clear, and deep Christianity, believes there is only one God, the risen savior, Jesus Christ. Timothy Keller asks a great question in light of this, "Why then, would such an exclusive belief system lead to behavior that was so open to others?" In his book The Reason for God, he gives us the answer:
"Christians, within their belief system, had the strongest possible resource for practicing sacrificial service, generosity, and peace-making. At the very heart of their view of reality was a man who died for his enemies, praying for their forgiveness."
Christianity, is not like exclusive country clubs and resorts. Believing there is only one true God, Jesus Christ, gives us a model to be the most welcoming of people. The most generous of people, constantly working for peace in our neighborhoods, families, and world. We can actively bring peace to others because our God has actively brought peace and forgiveness to us.