I seem to remember reading somewhere that Catholics are not allowed to speak of religion to non-Catholics that are obstinate and have rejected Catholicism, i don't mean disputing/debating/arguing/etc., but simply conversing about religion/God/spirituality with them, having conversations without any effort or intention to convert them or point out their errors and things like that. I can't remember at all where it was but i think im sure i did read it in some pre-Vatican 2 book. I think there was actually some penalty for doing this.

Does anyone have any idea?

It's not Mortalium Animos because this deals specifically with public gatherings, conventions etc. of many people and things of that nature, not with simple private conversations.

Catholics are not allowed to speak of religion to non-Catholics  
 

This is nonsense. How do the non Catholics learn about is if we remain silent?

I specified in my post that I was referring to obstinate non-Catholics or those who have already rejected Catholicism.

The principle that Catholics would be forbidden from coercion of non-Catholics is contained in Vatican II docuмents.  It was one of the Vat.II novelties.  It was a way of making the intention to seek conversions into a nefarious or repugnant agenda, as if it violates the privacy of pagans or whatever.  The current program of Pope Francis is merely the latest development of this false principle.  

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I think I see what you are getting at OP.  It made me think of "dusting off one's sandals".  I don't know what docuмent you may be referring to, but I think the idea is that it is more dangerous to our own faith to converse with such people.

Just searched the interwebz and found this:

http://www.catholicapologetics.info/modernproblems/ecuмenism/noncath.htm

Clearly, most of what is on this website is not possible in a non-Catholic society.

It can be dangerous to expose oneself to non-Catholic doctrines which necessarily happens when one discusses the faith with non-Catholics.  So one who is not very knowledgeable should not be debating with non-Catholics in an attempt to convert them.

Quote from: 2Vermont

Just searched the interwebz and found this:

http://www.catholicapologetics.info/modernproblems/ecuмenism/noncath.htm

Clearly, most of what is on this website is not possible in a non-Catholic society.

It can be dangerous to expose oneself to non-Catholic doctrines which necessarily happens when one discusses the faith with non-Catholics.  So one who is not very knowledgeable should not be debating with non-Catholics in an attempt to convert them.

I think I see what you are getting at OP.  It made me think of "dusting off one's sandals".  I don't know what docuмent you may be referring to, but I think the idea is that it is more dangerous to our own faith to converse with such people.

You're both misunderstanding what I'm saying.

I'm talking about someone who is Catholic and has no doubt about anything, talking about religion and God etc. to a Protestant as if the Protestant were another catholic, without any attempt of pointing out his errors etc. It's not debating or arguing.

CODEX IURIS CANONICI
CAN. 1325.
   § 3. Caveant catholici ne disputationes vel collationes, publicas praesertim, cuм acatholicis habeant, sine venia Sanctae Sedis aut, si casus urgeat, loci Ordinarii.

Catholics are to avoid disputations or conferences about matters of faith with non-Catholics, especially in public, unless the Holy See, or in case of emergency the Ordinary of the place, has given permission (c. 1325, §3).

This encyclical may be of interest to you
http://traditionalcatholic.net/Tradition/Pope/Pius_XI/On_The_Promotion_of_True_Religious_Unity,_January_6,_1928.html

    "The faithful are bound to profess their faith openly whenever under the circuмstances silence, evasion, or their manner of acting would otherwise implicitly amount to a denial of the faith, or would involve contempt of religion, an offense to God, or scandal to the neighbor (c. 1325, §1)."  - Commentary on Canon Law