Constantine the Great
Constantine did not support Christianity alone.  After winning the Battle of the Milvian Bridge, he built the Arch of Constantine) to celebrate, but the arch was decorated with pictures of sacrifices to gods like Apollo, Diana, or Hercules.  It had no Christian symbolism.  In 321, Constantine said that Christians and non-Christians should all join the "day of the sun" (the eastern sun-worship which Aurelian had helped him introduce). His coins also had symbols of the sun-cult until 324. Even after pagan gods disappeared from the coins, Christians symbols never appeared on the coin, either. Even when Constantine dedicated the new city of Constantinople, he was wearing the Apollonian sun-rayed Diadem.