The Bronze Serpent Moses was commanded to make in the wilderness had the purpose of "pointing to Jesus the Messiah." — John 3:14-15
Idolatry is when "good" things become more important than "God" things... aka "following Jesus." — Exodus 20:3
Heaven is not a place for "good" people. It's a place for "God's" people. Following Jesus is much more than being involved in "good deed." — Matthew 7:21-23