Don't Bother Praying for Those Who Commit the Unforgivable Sin

In 1 John 5:16-17, John says this: "If anyone sees his brother committing a sin not leading to death, he shall ask and God will for him give life to those who commit sin not leading to death. There is a sin leading to death; I do not say that he should make request for this. All unrighteousness is sin, and there is a sin not leading to death." The sin leading to death is the unforgivable sin. There is no point in praying for the person who has committed this sin? Why should we if God has already declared He won't forgive it? What is the unforgivable sin? We will look at this subject in this sermon.