The Roman's preferred to adopt everyone's God's, and building Temples to each one. As they had adopted the Greek God's giving them Latin names e.g.:
Zeus (King of the Gods) became Jupiter.
Poseidon (King of the Sea) became Neptune.
Ares (God of War) regarded as the father of the Roman people because he was the father of Romulus, co-founder of Rome (850 B.C.) with Remus, became Mars.
Apollo (messenger of the Gods) became Mercury.
Aphrodite (Goddess of Love) became Venus.
Gods named for Days of the Week
The following Days of the Week are after Greeco-Roman, Norse, and Germanic Gods:
Sunday – Day of the Sun.
Monday – Day of the Moon.
Tuesday - Tyr or Tiw was the Norse God of War. Also known as Martius Roman God of War.
Wednesday - Mercury the messenger God. Also known as the Norse God Odin, and Woden or Wotan to the Germanic Tribes.
Thursday - Thor was the Norse God of Thunder. And Jupiter also chief of the Gods.
Friday - Fria Norse God (in this case a goddess). She was believed to be the wife of Odin and was the goddess of marriage and the hearth. The Roman's had named this day for Venus their goddess of beauty.
Saturday - Saturn Roman God of Time and the Harvest.
Gods named for Months of the Year
The original Roman year had 10 named months Martius "March", Aprilis "April", Maius "May", Junius "June", Quintilis "July", Sextilis "August", September "September", October "October", November "November", December "December".
January: Janus is the Roman god of gates and doorways, depicted with two faces looking in opposite directions. His festival month in January.
February: Februa is the Roman festival of purification, held on February fifteenth. It is possibly of Sabine origin.
March: Martius was the time for the resumption of war. Mars is the Roman god of war. He is identified with the Greek god Ares.
April: Aprilis is the month of Aphrodite the Greek goddess of love and beauty. She is identified with the Roman goddess Venus.
May: Maia (meaning "the great one") is the Italic goddess of spring, the daughter of Faunus, and wife of Vulcan.
June: Junius or Juno is the principle goddess of the Roman Pantheon. She is the goddess of marriage and the well-being of women. She is the wife and sister of Jupiter. She is identified with the Greek goddess Hera.
July: After the first Roman Emperor Julius Caesar (100-44 B.C.), who was regarded as a God.
August: After the second great Roman Emperor Augustus Caesar (63 B.C.-14 A.D.), who like all Emperors up until Constantine (274-337 A.D., the first Christian Emperor) was also regarded as a God.