This idea contains the four main doctrines on the Bible: that its teaching is needed for salvation (necessity); that all the doctrine necessary for salvation comes from the Bible alone (sufficiency); that everything taught in the Bible is correct (inerrancy); and that, by the Holy Spirit overcoming sin, believers may read and understand truth from the Bible itself, though understanding is difficult, so the means used to guide individual believers to the true teaching is often mutual discussion within the church (clarity).