If you think you are saved by having a proper understading of the five points of calvinism, or by getting your understanding of the extent of the atonement right, you have missed the Gospel by adding to it.  These are certainly important topics.  They are issues that the true believer will endeavor to "get right."  However, your understanding of these things is not the Gospel.  The puritan John Bradford once wrote, "Let a man go to the grammar school of faith and repentance, before he goes to the university of election and predestination."  Now while I still believe that election and predestination are core gospel truths, and anyone that denies these things is denying the Gospel, these are still not a requirement to understand in order to be saved by Jesus.