Do Christian disciples use symbols in worship?

“‘Therefore, get out from among them, and separate yourselves,’ says Jehovah, ‘and quit touching the unclean thing’”; “‘and I will take you in.’” — 2 Corinthians 6:17

Symbol of the cross
Use of the cross in worship, has pagan origins. Hundreds of years after the death of Jesus, Christian churches deviated from his teachings and new church members “were permitted largely to retain their pagan signs and symbols,” including the cross.

Symbol of the fish
Ichthys (Koine: ἰχθύς (ikhthýs) is the Greek word for "fish". In Greek mythology, Ichthys was the offspring son of the ancient Sea goddess Atargatis, and was known in various mythic systems as Tirgata, Aphrodite, Pelagia or Delphine. The word also meant "womb" and "dolphin" in some tongues, and representations of this appeared in the depiction of mermaids. The fish is also a central element in other stories, including the Goddess of Ephesus (who has a fish amulet covering her genital region), as well as the tale of the fish that swallowed the penis of Osiris, and was also considered a symbol of the vulva of Isis.
 * Ichthys

In Philistia, the Philistines worshiped a fish-shaped god, known as Dagon. The name derives from the Semitic root dag, meaning "little fish". Dagon is mentioned in the Hebrew Bible at the temple of Azotus (1Sa 5:4). Coins of various Philistine or Phænician cities, on most of which Dagon is represented as a composite figure, human as to the upper part of the body, fish-like as to the lower. From this it may well be inferred that Dagon was a fish-god. His face, hands and a portion of his body resembled that of a fish, in accordance with the most probable interpretation of "the stump of Dagon" (verse 4). Dagon is sometimes associated with a female half-fish deity, Derceto or Atargatis, often identified with Astarte.
 * Dagon

Mosaic law principles
Jehovah God made a covenant with the Israelites in Horeb to not form any symbol, so as to represent anything in heaven or on the earth, including fish


 * Torah

[15] “Therefore, watch yourselves closely—since you did not see any form on the day Jehovah spoke to you in Horeb out of the middle of the fire— [16] that you may not act corruptly by making for yourselves any carved image having the form of any symbol, the representation of male or female, [17] the representation of any animal on the earth or the representation of any bird that flies in the sky, [18] the representation of anything creeping on the ground or the representation of any fish in the waters under the earth.