Liberal theology had often denounced the idea of substitutionary atonement as barbarous. Sometimes an effort was made to claim it was unbiblical through certain definitions of huper. For example, note Paul's statements: "We are convinced that one has died for (huper) all" (2 Cor. 5:14; cf. 5:15), and "Christ died for (huper) the ungodly" (Rom. 5:6). The argument against vicarious atonement at this point was that huper does not mean substitution. But what Robertson found from his reading of ancient Greek documents is that huper very, very frequently means substitution. It refers to someone doing something for another or in another's place. If someone could not write, a scribe would write the letter for them. Thus recent Greek dictionaries define huper as "for, in behalf of, for the sake of someone, in place of, instead of" for some of its most common meanings.
Robertson concluded: "No one of the theories of the atonement states all the truth nor, indeed, do all of them together. The bottom of this ocean of truth has never been sounded by any man's plumb-line. There is more in the death of Christ for all of us than any of us has been able to fathom....However, one must say that substitution is an essential element in any real atonement....It is futile to try to get rid of substitution on grammatical arguments about huper" (p. 41). And there is the beautiful truth. Jesus died for you, in your behalf, for your sake, in your place, and instead of you so that you could be spared eternal death and enjoy eternal life.