Sabine Baring-Gould

“ The time of repentance was past, and the punishment threatened must fall.
And now perhaps you can understand a saying of S. John in his first Epistle. He says:—"If any man see his brother sin a sin which is not unto death, he shall ask, and he shall give him life for them that sin not unto death. There is a sin unto death, I do not say that he shall pray for it." ”

“ S. John is not speaking here of what we call mortal sins, but of mortal sins continued till the measure is filled up, and when the last sin has been added which completes the measure, that is the sin unto death, which it avails nothing to pray for, for that sin ends in death. Before, there was life, spiritual life, perhaps flickering, but extant, then comes the last sin, and the life is gone out, all is dark, and dead, and cold, no more fanning of the black ashes is of any avail, the fire is out and cannot be revived. ”

“ God said, "thy seed shall come hither, for the iniquity of the Amorites is not yet full." Now actually it was not till four hundred and seventy years later that the destruction of the Amorites was accomplished. Four generations after Abraham, that is some two hundred and forty years after, the measure of their iniquities was full, and yet they existed on till Joshua crossed Jordan with the Israelites, and then they were all put to the sword.
In the New Testament we hear the Jews addressed as though they also had a measure of sin they must fill up before God would forsake them. ”

“ If He fixes a bound to nations, beyond which they cannot go without His forsaking them, it is because there is the law, which is of general application to all human beings; a law applying to single persons, and to persons in the aggregate. ”