I was watching the predestination debate between Micheal Brown and James White and James said something that intrigued me and i hd never thought of before.
Did Jesus’ work on the cross cover the unforgivable sin of blaspheming the Holy Spirit?
Also was the sin of “unbelief” covered? And if so, is it possible to not be saved?
I think your confusion comes the plural use of the word sin. Jesus did not die for sins, but sin.
2Co 5:21 For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him.
Notice the verse is all in the singular. He became sin who knew no sin because we are sin. Because we are sin, we are sinners creating more sins in the plural.
What does "unbelief" mean biblically? It means not believing the truth of God, and believing lies instead. Can we have unbelief and belief at the same time? Sure, we can, and we all do. If we didn't all believers would operate in the miraculous all the time, which is not the case. Unbelief can mitigate our belief in Christ, but it does not remove our faith in Christ.
Which brings us to the unpardonable sin. What is it? Jesus said it in Matt 12:32 & 32.
Mat 12:31 Wherefore I say unto you, All manner of sin and blasphemy shall be forgiven unto men: but the blasphemy against the Holy Ghost shall not be forgiven unto men.
Mat 12:32 And whosoever speaketh a word against the Son of man, it shall be forgiven him: but whosoever speaketh against the Holy Ghost, it shall not be forgiven him, neither in this world, neither in the world to come.
As they say, a verse out of context is a pretext. So what is the context of what Jesus said? He was responding to what the Pharisees had said.
Mat 12:24 But when the Pharisees heard it, they said, This fellow doth not cast out devils, but by Beelzebub the prince of the devils.
Basically, the Pharisees were calling God (the Holy Spirit) the Devil (Beelzebub). What was unforgivable wasn't the statement. It was the belief behind the statement.
Isaiah said:
Isa_5:20 Woe unto them that call evil good, and good evil; that put darkness for light, and light for darkness; that put bitter for sweet, and sweet for bitter!
The writer of Hebrews also said:
Heb 6:4 For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,
Heb 6:5 And have tasted the good word of God, and the powers of the world to come,
Heb 6:6 If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.
What all this means is that if a person comes to the point of rejecting Christ and convinces themselves, like the Pharisees had, that God is actually evil, and genuinely believe that the devil is good, there is no more chance of repentance and forgiveness. It is a line crossed with no turning back. They have become true reprobates whose hearts towards God is now completely hardened against God.
Our salvation rests upon one thing only, not our works but who we are. In Adam we are sin, in Christ we are his righteousness. Our fight of faith is to hold onto that one truth. Christ fully satisfied the requirements of God for righteousness and has freely given his righteousness to all will accept it.
The devil and the world system assault this foundation by putting responsibility for our salvation upon us in terms of works. But those who walk with Christ see his goodness as he pours his blessings on us daily. It is the goodness of the Lord the leads us (and keeps us) in repentance.
PS
The number 1 assault on our faith is slander by the devil against God. The devil wants us to believe that God is mean, wrathful, a rewarder of works only, who is never pleased with us. It began in the Garden of Eden, "Has God said..." was meant to cause doubt in God's good intentions towards Adam and Eve. And he continues in this same strategy. Our struggle of faith is in resisting these lies and holding fast until the end of our lives, the incredible goodness of the Lord.
My personal hero, Polycarp, was told that if he repudiated Christ he would not be executed. He responded, "Eighty and seven years the Lord has been good to me, how could I deny him now?" Polycarp understood that God had always been good towards him, even before he came to faith in Christ.