Shared ground
Mark presents a real question about religious practice: other serious groups fast, but Jesus’ disciples do not (v. 18). Jesus answers by shifting the issue from “Which rule?” to “What time is it?” His first image is explicit: his presence is like a bridegroom at a wedding, where fasting would not match the moment (vv. 19–20). He also explicitly predicts a change: when the bridegroom is “taken away,” his disciples will fast (v. 20).
The cloth and wineskin pictures reinforce a basic point the text states clearly: mixing “new” and “old” in the wrong way ruins both (vv. 21–22). Whatever Jesus is bringing cannot simply be attached as a patch or poured into existing containers without damage.
Where interpretation differs
Some readers take the cloth and wineskin images as directly explaining fasting: Jesus is saying old fasting patterns do not fit the new situation he brings, though fasting will have a place later (v. 20).
Others think the images widen the topic beyond fasting. On this reading, fasting is the trigger question, but Jesus is mainly talking about the larger mismatch between his mission and certain established patterns of religious life; fasting is one example of a broader “new vs. old” tension.
A smaller difference concerns “taken away” (v. 20). Some read it as hinting at a sudden, violent removal (pointing ahead to his death). Others read it more generally as his departure from them, without specifying how.
Why the disagreement exists
The passage gives two sets of images (wedding; cloth/wine) without explicitly spelling out the exact one-to-one mapping for the “old” and the “new.” Mark records the sayings, but he does not add a direct explanation of what each item represents. That leaves readers deciding how tightly vv. 21–22 connect to fasting and how specific the prediction in v. 20 is meant to be.
What this passage clearly contributes
Explicitly, Jesus identifies himself with the “bridegroom” and treats his presence as a decisive moment that changes what is appropriate (vv. 19–20). He also makes room for both present feasting-like joy and later fasting, depending on the situation (v. 20). By adding the cloth and wineskins sayings, the passage contributes a second clear claim: Jesus’ “new” reality cannot be safely combined with “old” forms in an unthinking way; forcing the fit causes loss (vv. 21–22).