If one fears he has committed the unpardonable sin, he need not worry; belief in the Lord Jesus Christ and one's regret of sin, and desire for forgiveness, testify to his eternal salvation.
So often I get caught in shame and despair. There is no need for that, either; God has forgiven me, so I should rejoice. Doubt and unbelief and rejection are all tools of Satan.
"All that the Father giveth me shall come to me; and him that cometh to me I will in no wise cast out." -John 6:37, KJV
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I do not intend to tread on anyone's toes. These are the things I know, and if God is willing may bring someone peace in these reminders.