If you believe that Jesus died for your sins, that He was buried and rose again according to the Scriptures, you have been given that faith by the Holy Spirit (Jn. 16:8-13; 1 Cor. 15:3-4; Eph. 2:8). In other words, the Holy Spirit is still working to bring you to Jesus; you have NOT committed the unpardonable sin. Remember, He is God, and as God, He knows when your rejection of Jesus is final (Acts 5:3-4). If He is still convicting you, then the last time you said no, He knew that it was "not your final answer."
What about a Christian; can he commit the unpardonable sin? The answer to this question is clearly “NO.”
"...whosoever believeth in Him should not perish, but have ETERNAL LIFE. For God so loved the world, that He gave His only begotten Son, that whosoever believeth in Him should not perish, but have EVERLASTING LIFE. For God sent not His Son into the world to condemn the world; but that the world through Him might be saved. He that believeth on Him is not condemned: but he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God" (Jn. 3:15-18).
Notice that the verb, "believeth," is present tense. The believer need only ask himself, "Do I believe (place my complete trust) in Jesus?" If the answer is yes, he has not committed the unpardonable sin; he is saved. Paul wrote in 1 Corinthians 12:3, "Wherefore I give you to understand, that no man speaking by the Spirit of God calleth Jesus accursed: and that no man can say that Jesus is the Lord, but by the Holy Ghost."
Blasphemy of the Holy Spirit, the rejection of His gift of faith in Christ, is rooted in the heart of man (Matt. 12:35). Our words reflect the inner condition of our heart. On the Day of Judgment, man will give an account of every word (Matt. 12:36). Our words give evidence of our true spiritual state. “Out of thine own mouth will I judge thee, thou wicked servant” (Lk.19:22). Just as the blasphemy of the Holy Spirit indicates a hardened heart to the Gospel, the believer’s speech should bear witness to his new life in Christ (Col. 4:6). Let every believer use his voice to bring glory and honor and praise to our God and Savior, Jesus Christ. AMEN!