'Necessary' in the Bible

If anyone thinks he knows anything, he has not yet known as it is necessary to know.

For indeed it is necessary that there be factions among you, in order that those who are approved may become evident among you.

But by much more the members of the body which are thought to be weaker are necessary,

For it is necessary for him to reign until he has put all his enemies under his feet.

For it is necessary [for] this perishable [body] to put on incorruptibility, and this mortal [body] to put on immortality.