It means Lions beat the Christians 10 times (it literally means 10 points), and the Christians beat the Lions 0 times (literally nil (0) points). Obviously to say 10 times here assumes 1 point per win. Whether the Lions are meant to be the atheists or not, the context will show.
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SweetFreedomLions 10; Christians nil~ Lions 10; Christians 0.
This is a very old joke. I recall seeing a TV program back in the 1970s (Monty Python?), which had a sketch set in ancient Rome. There was a scoreboard saying "Lions 103, Christians nil".