Ash Wednesday ushers the start of Lent, a six-week period where Christians prepare for Easter through prayer and reflection. For Catholics, the season also involves fasting on certain days and abstaining from meat on Fridays. The tradition, which started in the early church, is something that Catholics, and many Christians in general, have prescribed to for centuries.

Catholics avoid meat during Lent to show respect for the death of Jesus. There have been exceptions in the past, like dispensations when St. Patrick’s Day falls on a Friday during the Lenten season.

Fish, on the other hand, is permitted. It’s the reason why fast food chains like McDonald’s have for decades aggressively advertised the Filet-O-Fish, a sandwich invented in 1962 to cater to Catholics looking to avoid meat on Fridays and to make up for sagging burger sales. (Now Arby’s has jumped into this market.)

Thanks to products like the Impossible Burger or Beyond Meat, the dietary restrictions that come with Lent have been turned on their head. Plant-based imitation meat alternatives look and taste like meat — but isn’t. That has unleashed a meaty debate in pews and on message boards over whether plant-based patties can or cannot be eaten during Lent and whether doing so is a sin.

“As someone who eats and craves meat, I see not eating meat as a sacrifice,” wrote one Reddit user. “Though it may be OK to eat, it is a small sacrifice compared to Jesus dying for our sins. I will try the burger, but not on a Friday or Ash Wednesday in Lent.”

Others disagree, saying if it isn’t meat then it’s fair game.

“I would think that it is against the spirit of the requirement, but it wouldn’t be a sin because it is not a violation of the church law,” wrote another user.

The debate isn’t limited to Roman Catholics. Orthodox Christians who belong to Eastern Rite churches also fast and abstain from meat (and dairy) throughout Great Lent and at other times of the year. Jews who keep kosher have also had to face the religious predicaments that these foods now present.