Disclaimer about sending mixed messages to players
Building up intrigue about the door, so that it has a payoff later in the story, works in many game and storytelling contexts. But it doesn't always work well in TTRPGs, when players are naturally curious and tend to manipulate their world as much as possible.
In general, when the DM draws attention to something in the players' environment, they are effectively communicating to the players that the thing is important and deserves their current focus. By making the players curious about the door, they will want to investigate it and know what's behind it.
Trying to tell your players "This thing is really interesting, but don't investigate it too much" is a mixed message that may confuse and frustrate your players, or make them feel like you are teasing them. Sure, you the DM intend for the door to become relevant later on. But this is a problematic assumption. First, it's possible that the player actions may derail the campaign from the story you planned. Second, the players don't know your future plans, so they will likely try to open it now.
Recommendation: Draw attention away from the door.
D&D players will gravitate toward the most interesting thing in their environment. If the most interesting thing is the door, then they will focus on the door and how to open it. If the most interesting thing is not the door, then they will stop focusing on the door.
Distract the players with something else of a higher priority, thereby drawing focus away from the door. Considering that you intend for the door to become relevant later, you probably want the players to go somewhere else first; find a way to draw the players in that direction. If the players spend too much time poking at the door, you could have some event, NPC, or other plot device that encourages the players toward where you want them to go next.
Some example distractions:
A fight starts outside the temple, and someone cries for help.
A messenger arrives, and tells the PCs that the mayor needs to speak with them right away.
A temple priest tells the PCs to stop disturbing the area.
The PCs find another temple area (possibly another door) that gets their attention.