"In the Mouths of 2 or 3 Witnesses Shall a Thing Be Established" (2 Cor. 13:1)
In these words, by Paul to his brethren in Corinth, we have another key to understanding the Bible. Every vital doctrine of God is stated in more than one place in His Word.
There are many facts mentioned only once in the Bible. But to take one of these facts and develop a doctrine is scripturally wrong. This has been done by many groups. A good example of this wrong doing is found in the words of Paul (1 Cor. 15:29), "Else what shall they do which are baptized for the dead, if the dead rise not at all? Why are they then baptized for the dead?"
This is the only place in the Bible where we find the phrase baptized for the dead. It is taken by some to mean that the living can be immersed (baptized) for those that are now dead -- the dead, by proxy, being baptized. The context of this verse shows that Paul is not teaching this doctrine and the original Greek words which he used deny it also. Paul, instead, is teaching the necessity of resurrection.
If there is no resurrection, then Christ is not risen, and those in Christ are perished (verses 12-18). Therefore, if this is the case, why should anyone become a believer and be baptized to take the place (or, fill the ranks, as the Greek says) of the believers that had died.
Notice his next question (verse 30) "And why stand we in jeopardy every hour?" There was no jeopardy in being immersed. The jeopardy was in living the Christian life in that day when believers were thrown to the lions. Why fill vacated ranks created by the deaths of Christians if there would be no resurrection to eternal life?
Another example of creating false doctrine upon one solitary verse is found in Revelation 20 where some have developed the doctrine of separate resurrections and judgments for the righteous and unrighteous. Jesus says "Marvel not at this: for the hour is coming, in the which all that are in the graves shall hear his voice, and shall come forth; they that have done good, unto the resurrection of life; and they that have done evil, unto the resurrection of damnation" (John 5:28,29). We also read (Daniel 12:2) "And many of them that sleep in the dust of the earth shall awake, some to everlasting life, and some to shame and everlasting contempt." Here we have Jesus and Daniel saying the same thing -- the righteous and evil both rising out of the graves and standing judgment at the same time. And since this doctrine is corroborated it is a valid and vital doctrine of Deity.
Remember the words of Paul, "In the mouth of two or three witnesses shall every word be established". This will help you discern true doctrine.