Consider this - in the Middle Ages nobody could read the scriptures except for Latin priests - does this mean that everyone who considered themselves a Christian, yet didn't understand what it meant to be in a "relationship with God" (but that the extent of their understanding was what they were taught by the hierarchy - that you had to put money into the offering tombs to go through Limbo and into Heaven) didn't believe in the 'Christian God'? That term is misleading, because modern, Pentecostals have hijacked the term 'Christian' and added their own requirements as to what constitutes a Christian.
Chances are, and I was guilty of this myself in my younger years, your view that salvation is a central theme to Christianity is something you heard in Church, because so many pastors in services today (after the explosion of Billy Graham/Ray Comfort Pentecostalism) emphasise that Jesus died for our sins and rose again on the third day etc... But from an objective reading of the Bible, from start to finish (and note that liberalism also challenges the selection of books for canonical inclusion as well), you would not be able to come to the conclusion that the sermons leading up to the altar calls you hear today are reflective of the Christianity that Jesus taught.
Look at all the people Jesus interacted with when He was on Earth. Most of them knew nothing about God, about what it meant to be a 'follower of God', anything they did after meeting Him is entirely speculative (the adulteress who He didn't condemn) and the people in His parables who went to Heaven or were accepted by God, e.g. the Good Samaritan, the poor man Lazarus - none of them were indicated to have any concept of having a relationship with Him or accepting Him as their Lord and Saviour and thus 'saved' besides their good works.
Ask yourself questions like - how come the words Free Will never appear in the Bible? Yet it is supposedly such an incredibly central theme to why we must accept Jesus Christ. Or how about the concept of 'relationship with God'? Or the Trinity? A lot of what we believe about the Trinity today is very vague if you look at what the Bible actually says about it. Christians say things like: "The Holy Spirit told me to do this", or, "the Holy Spirit led me to go to university to study medicine". Yet there is very little scriptural authority for what the Holy Spirit actually does.
You really have to study theology and its history to see how much Christianity has changed, and how modern Christianity has become so Pentecostalised to the point that when people from the outside look at Church today - a venue for loud music and entertainment and tongue speaking and "falling over", a group of people who want their right to smack their kids and have intelligent design taught in school and the Ten Commandments posted in the Courts, are against abortion, homosexuality and only 40 years ago the segregation of black and white people, and how you must repent or you will go to Hell because God cannot accept your sin unless you acknowledge Him and no-one has any excuse - you can see that there is something definitely wrong with how Jesus' values have been reflected over the centuries.