Then tell me why it requires a real, physical event that affect other people in order for it to be a sin? What is that real, physical event?
...I don't see where ICANT has ever made such a claim. I think you may be attacking a strawman.
ICANT does not claim that specific actions of any sort are sins -
disobedience to God is a sin. Thus murder, theft, eating meat on Friday, or planting flowers in your yard can be sinful or not sinful depending on God's instruction.
The "unforgivable sin" of blasphemy against the Holy Spirit seems to be, in ICANT's view, ending your life denying God's existence and rejecting his offer of a full free pardon. Basically,
allsins are pardonable and forgivable so long as you accept the gift of forgiveness.
Jesus instructed that even thinking lustfully about a woman is sinful because you disobey God's commandment against adultery in your heart. There's no physical act necessarily involved.
That about right, ICANT?
The idea that a sin must be a physical act that has a specifically detrimental effect on other people is not the Christian concept of sin. You're thinking about a very different, non-authoritarian, practicality-based system of ethics. The "love thy neighbor" and related commandments ensure that the two have a lot of overlap, but they aren't the same at all. Even the idea that God's commandments are intended to be what we would consider ethical (ie, reducing net harm to others, etc) is not Biblical.
The concept of sin is
amorally authoritarian. It can resemble morality when the authority figure gives certain instructions (thou shalt not kill/steal/lie/etc), and can appear to be immoral when the authority figure gives other commands (kill all the firstborn). It's all about doing what God says, period. Disobedience to those commands is sin, whether that matches a reasonable system of ethics or not.