Jesus mentioned the blasphemy against the Holy Spirit, but had not yet sent the Holy Spirit, and the sin at that moment Jesus spoke was a Hebrew leader, maybe a Pharisee saying the finger of God, in driving out demons, was really Satan.
One can blaspheme by simply doubting God exists. To say God doesn't exist is a blasphemy.
Hebrews 6 tells us that after a person has tried and tasted all the blessings of the Holy Spirit, all the graces that move a person to repent and be loving... then the heart that is hardened to these graces cannot again be brought to repentance, otherwise he or she is saving his or herself.
So even Paul the apostle before he tasted the power of the resurrection could not commit the eternal sin, because he was immature and another avenue of grace could reopen for him the way to repent again.
You can receive Jesus' blood, and sin again, and receive Jesus' blood and be cleaned again, and again all your life. But if you harden your heart instead of receiving Jesus blood, when it is actually on your presence, then you need strong self discipline, to crunch, chew up your hardened heart to softness to God's word to be soft and responsive again. Obeying crunching. Or God's love can soften your heart. This again, when you hunger, and understand, and no rush, ask and the love like in Romans 5:5 is actual and local to you, pours into your heart. It changes you.
So leaving some aspects of the Holy Spirit for maturity and look for Living water, oil and the blood of the Lamb for now.