Deuteronomy 4:15
Deuteronomy 4:1515So since you saw no form of any kind on the day the LORD spoke to you out of the fire at Horeb, be careful
The Watchtower cites as reinforcement of a blanket ban on religious images. Moses's warning — "you saw no form of any kind on the day Jehovah spoke to you at Horeb" — is read as proof that any representational art used in a religious setting is forbidden, which in turn licenses the Watchtower's prohibition on crosses, nativities, and depictions of Jesus (Reasoning From the Scriptures pp. 183-187).
Moses's concern is exact and limited: do not make an idol in the form of male, female, beast, bird, fish, or creeping thing for devotional use, because "you saw no form of any kind on the day Jehovah spoke to you." The target is representing Jehovah, who has no seen form, for cultic worship. The same God then commanded cherubim on the ark (), cherubim in the temple curtains (), and a bronze serpent on a pole () — and Jesus later used that bronze serpent as the pattern for his own crucifixion (). If banned representational art as such, the tabernacle and temple would have been the most idolatrous buildings on earth. The prohibition falls on cultic images used for worship, not on teaching aids, memorial symbols, or historical depictions. Every Watchtower magazine illustration of Jesus operates on exactly this distinction; the rule cannot consistently apply only to outsiders.