It is doubtful that anyone living in the United States has committed the unforgivable sin.  It's possible, but since we have complete religious liberty, it's doubtful.

Sin, is not a difficult concept...God laid out ten simple rules for us to follow; break the rules and you've sinned.  Pretty simple stuff.

Do Not Be Deceived:  God hates sin and sinners will be punished...don't fall for the myths lies and misconceptions preached today.  All your sins past, present and future are not forgiven.  Jesus didn't die for your sins, he died for the sins of the world; his death wiped the slate clean, but not one jot or tittle of the law passed away.  The wages of sin, is death (Romans 6:23)

Don't be fooled into thinking "heaven" is your final reward.  It's not about "heaven," "Heaven" is just a resting place.  it's about judgement; whether you will receive eternal life or eternal damnation...and that depends on how you live your life.

So, what is the unforgivable sin?  When you know, without a doubt, God is real...you can only know that if it is revealed to you by the Holy Spirit thru the experience of Spiritual birth.  If you've been "born again," you know, without a doubt, God is real...so you can no longer deny it.  If you do, (even under extreme persecution or threat of death) that makes you a liar...and all liars will burn in the lake of fire. (Revelation 21:8)

Until you know, without a doubt, God is real...nothing else matters.