Misinterpretations often detach this verse from its historical context of God's specific covenant with Israel for the conquest of Canaan, leading some to apply it as a blanket promise of fearlessness against any modern personal or national enemies without regard for obedience or divine will; others misconstrue 'terrible' as God being cruel or monstrous, overlooking its biblical sense of majestic awe and power that evokes reverence.
Deuteronomy 7:21
King James Version (1769)
21 Thou shalt not be affrighted at them: for the Lord thy God is among you, a mighty God and terrible.
God encourages the Israelites not to fear the formidable Canaanite nations they face in conquering the Promised Land, assuring them of His powerful presence among them as a mighty and awe-inspiring God who will deliver victory, emphasizing dependence on divine strength and protection rather than human might in fulfilling His covenant promises.