Two things to address...
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One
No, having someone else tell you what your PC feels does not upset the general game philosophy. First of all, because you specifically asked them to do this specific thing. It's the classic case of a specific and circumscribed rule that modifies/trumps a more general rule. Secondly, it's ok because you might have this flash of insight about what your heart tells you... but then YOU get to decide what to do with it. Follow it? Ignore it? Challenge it?
The effect is akin to people that toss a coin to see if Heads or Tails comes out. Maybe because in this one instance they don't want to decide, so a random/external outcome is preferable to being forced to make a choice of their own. But maybe also because they know that having this external source pick an option for you might trigger your brain into revealing that, after all, you DID have a preference. You get Heads and go "oh no!" ... and that's your answer for you :)
For these reasons the World is free, and even encouraged, to mess with the PC. It makes no real difference. Tell them something random. Or stupid. Or extreme. Or tell them plain and simple what you (the World) would like to see them doing! It matters very little.
But... the implication that THIS is what their heart desires will often provoke a relatively strong reaction from the Player of the Priest, prompting active self reflection.
Maybe it could be formulated like this, for optimal effect:
ask the World what your heart tells you is the best course of action, then tell them how you feel about this revelation: is it (un)like yourself? is it an (un)welcome truth?
If you act on your heart’s advice, you gain Advantage.
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Two
Don't confuse the levels of the move ;-)
The PLAYER is indecisive and looks for external input... from the World, or a fellow Player, or a coin toss.
The PRIEST asks their deity for guidance.
The PRIEST gets an answer from within, from their heart, from their inner beliefs.
The PRIEST uses that input as their deity's answer.
In the fiction, the answer only ever comes from within. There is no external force. There is no deity. The point of the move is to have the Priest produce their own answer. The fact that at the table that answer came from the Player's mind or the World or another Player, is immaterial.
On another note... what you suggest is what the Priest does with the Signs and Portents move :)
The PRIEST sees something external (a person, a sunrise, a boat, a frog, whatever) and ascribes divine meaning to it.