Exclusive or All Inclusive?

Mark and I are reading "The Case For Christ: Student Edition" by Lee Strobel as he prepares for his role as Small Group leader for the 9th grade boys at our church.
We read a part the other night that really stuck with me. As I become more and more comfortable in my role as a Christian, I still struggle with the "who gets to go to heaven" part. It always seemed to me that when Christians claimed that only those who believe in and devote their life to Christ "get in" that it was really arrogant and not very accepting and welcoming. I knew that this truth was clearly stated in the Bible, but I still didn't fully understand it or feel good about it. Then we read it explained this way...and I am feeling a little better...
"One of Jesus' most outrageous claims is this "I am the way and the truth and life. No one comes to the Father except through me." (John 14:6) Of all the incredible statements Jesus made, this is the one I found most offensive. If anyone else had said it, he'd be blasted as exclusive, intolerant, and narrow-minded. It's one thing to claim to be "a" way-but the "only" way to God? That sounds pretty judgmental....But as I looked into the claims of Christianity, I discovered one big difference between it and other religions. Other religions are based on people doing something to earn the favor of God. They must perform good deeds, chant the right words...or faithfully follow other religious drills. By contrast, Christianity is based on what, according to the Bible, Christ has already done on the cross. According to the Bible, nobody can do anything to earn God's favor; rather, Jesus offers forgiveness and eternal life as a gift. Imagine two college frat houses. The first has a strict set of rules and allows in only people who have earned their membership....No matter how hard they try, a lot of people just wont make the cut. They'll be excluded. That's what every other religion is like...But the other house throws it's doors wide open and says, "Anybody who wants membership is invited inside! Rich or poor, black or white, honor student or rebel, we would love to include you. All you need to get in is to accept the invitation." That, according to the bible, is what Christianity is like."