Often, one hears the claim by some proponents of sola scriptura that "the Bible is all you need for salvation!" However, is this biblical? The answer is no.
For instance, in 2 Tim 3:15, we read:
And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through which is in Christ Jesus.
In this verse, Paul writes that Timothy knew the holy scriptures ([τα] ιερα γραμματα) since infancy, writings which were able (δυναμαι) to make him wise and lead to salvation. However, the Scriptures discussed in this verse are not Scripture in general (as in v.16), but the Old Testament texts (we will ignore the debate about the contents thereof; that is a debate for another day!). We could ask our Evangelical friends who raise the question posed at the beginning of this post, "If the Bible [read: both Old and New Testaments] are all that is required for salvation, was Paul wrong? Or maybe all we need for salvation is the Old Testament--it was enough for Timothy, after all!"
God uses many instrumental means to bring about salvation and to instruct us to maintain and grow in our relationship with him, not just the Bible (as important as that is); indeed, our Evangelical friends would agree that God can bring about salvation through the instrumentality of a one-page gospel tract that discusses John 3:16, or a good spiritual book, or simply a preached sermon, and that one continues to grow in their spiritual life through the instrumentality of the Church and other means too.
Additionally, there are many important issues any Christian faces that are not explicitly dealt with authoritatively in the Bible, including contraception, abortion in the case of incest or rape, artificial insemination, test-tube fertilisation, genetic engineering, surrogate motherhood, sterilisation, masturbation, sex education, eugenics, cloning, cremation, labour strikes, Christians and the military, etc. As the Bible does not cover these areas explicitly (and in many, not even implicitly), and without the guidance of an authoritative Church and modern revelation, how does a Christian know through their private exegesis of the Bible and conclusions on these topics they are truly glorifying God?
Fortunately, God has given us an authoritative Church and has gifted us with additional Scripture and revelation, and that Church is The Church of Jesus Christ of Latter-day Saints.