What is the difference between Taqwa (piety/God-consciousness), Khashyah (awe/reverence), Rahbah (dread/fear), Khawf (fear), and Raja' (hope), and how can one acquire these qualities, and why did Allah combine Khashyah (awe) with knowledge in His Almighty saying: "It is only those who have knowledge among His slaves that fear Allah (with Khashyah)"?

Taqwa (piety/God-fearingness) originally means for a person to create a shield between himself and what he fears. Islamically, it is the compliance with Allah's commands and abstention from His prohibitions. As for kashya (awe/reverential fear), it is fear coupled with knowledge and veneration. Therefore, Allah Almighty described scholars and prophets as possessing kashya. The two meanings converge in one who fears Allah and holds Him in awe in the unseen, by complying with His commands, abstaining from His prohibitions, and knowing and venerating Allah. True kashya cannot exist except through knowledge and veneration; the more one's knowledge of Allah increases, the greater their kashya of Him becomes.