I will try to briefly around the issue
Make it clear that I am not allowed to decide
1- You need to clarify if today a christian symbol as a cross is an idol,
There is a notion of association between idolatry and believing in g-d, there is a question about what is become of the christianity, there is a notion of an idol that was withdraw.
2- You need to clarify if the food itself has this form or the package only.
3- The object is an offering to an Idol or an Idol? An offering that has not been offered yet, and was manufactured by an idolatrous is prohibited.
In the guemoro (masseches Avoda zara, and a litle in Rosh Hashana) some utensiles with drawings. if they are not honorific are not prohibited.
4- there is a difference if the form is in relief or not.
All this was an invitation to explain the case.
But if the food is labelled by a Kashruss, all the questions are probably resolved.
Following the comment, I understand that the case is as follows:
1- the problem is In package. The packing is certainly not a recipient of great value. Moreover the image is printed and certainly not embossed.
-->In Shulhan Aruch Yoreh Deah 141 sayf 3, If they are utensils with drawings of idols, and not honorary utensils (package is intended to be thrown in the trash and is certainly not designed to be used for worship.). The package can be used because the drawings are only decorative.
2 - the Symbol is a Christian Fish Symbol, with a verse of new Testament.
---> In Shulhan Aruch (YD 141-6), the permission is clearly mentioned, even for an embossed figurine.
--> This specific fish is not the object of worship, but relates a (supposed) miraculous event.
3 --> A verse of New Testament is not an Avoda Zara. It is not Holly following the halocho, but not an object of A.Z. There is a problem with sifrey akum, books of non Jews (Yoreh Deah 139). But it is almost certain that it is not relevant here. it is not forbidden for a bookbinder to work on such books
Nevertheless I wish you good appetite.
------> It is perfectly kosher; is it tasty?