In order to commit an unforgivable sin, you must know the sin would or might be unforgivable before you committed it. Therefore, if you have never learned that a sin would or might be unforgivable before you committed that sin, you have not committed an unforgivable sin. There is only one general definition of unforgivable sin. It is a sin of blasphemotricity. (There are other words and phrases that mean the same thing as “blasphemotricity” and we shall discuss them at a later time.) So, what does the word “blasphemotricity” mean? Blasphemotricity is sin committed knowingly (knowing it is a sin), freely (without compulsion [without enslaving passion]) and repeatedly (with consciousness of continuance along a certain path) until one’s chances of forgiveness are used up.
Yes, God gives you only so many chances of forgiveness. Now, how do you know if you have used up all your chances of forgiveness? You know because you have died and are in hell. As long as you are alive and are not in hell, you have not used up all of your chances of forgiveness. However, another knowingly, freely committed, repeated sin may use up your last chance of forgiveness. You have been warned!
Note that an unforgivable sin is not limited to a specific sin but, rather, is any sin performed a certain way; that is, any sin committed knowingly (knowing it is a sin), freely (without compulsion [without enslaving passion]) and repeatedly (with consciousness of continuance along a certain path) and that uses up your last chance of forgiveness.
Finally, to begin a study of the Biblical basis for what you have just read, read Proverbs 29:1: “He, that being often reproved hardeneth his neck, shall suddenly be destroyed, and that without remedy.” Here is the IAV, spelling-updated KJV, version: “He, that being often reproved hardens his neck, shall suddenly be destroyed, and that without remedy.” Note the elements of the definition of blasphemotricity in this verse, as follows: “ He, that being often (that is, REPEATEDLY) reproved (that is, KNOWINGLY) hardens his neck (that is, FREELY), shall suddenly (that is, NO ADDITIONAL CHANCE OF FORGIVENESS) be destroyed, and that without remedy (that is, FALL INTO HELL). We will get into a precise, technical discussion later. For now, this provides you with what is most important for you to know.