God's TEN COMMANDMENTS are spiritual (Romans 7:14). Man is a tripart being, consisting of a body, soul and mind ( 1 Thessalonians 5:23). The spirituality of the TEN COMMANDMENTS is part of the overwhelming evidence of that fact. God made man in such a way that the core of his being, which spiritual, was designed to obey not the letter, but the spirituality of TEN COMMANDMENTS. In fact, when God created man, He wrote the TEN COMMANDMENTS in his soul (Romans 2:14-16).
It is the soul of a human which must obey the spirituality of the TEN COMMANDMENTS. Notice Christ's words in Matthew 5:21-28 wherein Christ basically stated that God's commandments against murder and adultery are violated in the soul apart from the acts. Since His laws are violated by the soul apart from the acts, then it is the soul who is required to obey His laws. Christ also informs us that God must be worshiped in the soul (sometimes called the spirit) (John 4:23).