There is no sin that is beyond pardon for God. 1 John 1:9 makes it clear that "if we confess our sins, he is faithful and just and will forgive us our sins and purify us from all unrighteousness."
So if that's the case, why did Jesus say that there is one sin that will deem a person unforgivable? Yes, that's in the Bible. It's found in Mark 3:28-29 where Jesus says "Truly I tell you, people can be forgiven all their sins and every slander they utter, but whoever blasphemes against the Holy Spirit will never be forgiven; they are guilty of an eternal sin."
Taken at face value, most people will think that this scripture means that if I say something bad about the Holy Spirit (even by accident), then we're practically going to hell no matter what we do. Sounds harsh right? Well, it also sounds wrong. That's because that's not what the Bible says.
Scholars will argue that there is more to the unforgivable sin that meets the eye, and just like any scripture, it cannot be taken at face value without proper study and contextualization.
It's best to start by looking at what's happening. Jesus is talking to Pharisees who say Jesus is controlled by the spirit of Satan or Beelzebub as He casts out a demon. Jesus is talking to Pharisees who have rejected the deity, person and work of Jesus Christ.
To blaspheme the Holy Spirit means more than just saying bad things about the Holy Spirit. It is characterised by a rejection of the work of the Spirit of God through the finished work of Christ. We don't blaspheme the Holy Spirit by just thinking bad thoughts about God's Spirit, but by rejecting the move of the Holy Spirit in our lives to bring forth the revelation of the God who has come to save us.
In this aspect, we understand more that God is one, and as we blaspheme and reject the Holy Spirit, we reject the whole trinity.
This statement is found all over scripture and is what we stand for as Christians -- that to reject the work of Christ inspired through the power of the Holy Spirit would mean spiritual and physical death, but to receive Jesus and then be sanctified by the washing of sins as we are anointed with the Spirit of God would mean eternal life with God.
There has only been and will always be only one sin, one mistake and one failure that will disqualify us from a life with God, and that is to reject God himself -- to reject the love of the Father, to reject the finished work of Christ and to reject the power of the Holy Spirit in our lives.
The unpardonable sin should not stir fear within the hearts of believers, but instead motivate us to continue to chase after the in-filling of the Holy Spirit that would bring greater revelations of who Jesus is in our lives so that we may put our faith and trust in Him until the time we come to meet the Lord face to face.
