(The common term would be heterodox, not heretical)
Here's an interesting article from Orthodoxinfo.com
Prayer With the Non-Orthodox
Related Articles
On Praying With Heretics
On the Burial of the Heterodox
Holy Canons Related to Ecumenism
Concerning Super Correctness
Metropolitan Philaret of New York
More related articles on Google!...
The Church forbids us to pray with non-Orthodox. When invited to a meal in a Protestant household, what do we do when they say "grace," e.g., the "Our Father" before a meal? (K.L., IL)
In this age of ecumenism, one is hard-pressed to argue with the "givens" of the religious world: "We all have the same God," or "All religions are good and are equal." If we apply these notions to science, it is immediately apparent that they are absurd: "All observations are valid and equal," or "Alchemy and chemistry are both sciences and are equal." Quite obviously, even within a given religious tradition, there are those who understand its precepts well and those who hardly grasp them. And so, a simple Orthodox believer would not claim to understand God with the same insight and perception that, say, a great Saint or Teacher of the Church understood Him; in a sense, in terms of their understanding of Him, these individuals have different experiences of God. How, then, since we consider Orthodoxy to be a correct statement about the nature of God, man, and the universe, can we actually have the same God as those whom we consider erroneous in their beliefs? Nor can any rational individual argue that all religions are equal. Even among modern religious traditions, some teach the ascendency of peace and love, while others advocate violence and even elevate it to the level of a "holy pursuit." The problem is, of course, that ecumenism is based on simple-minded or trendy notions of religion and the Truth. It thus forces us to confront complex philosophical and theological questions at a very low level, leaving little room for subtlety. In this context, praying with others takes on a special significance. Prayer is an expression of our Orthodox understanding of, and relationship to, God; therefore, we cannot engage in joint prayer with the non-Orthodox as an expression of a "commonality" with them which we in fact do not have. This fact is reinforced by Church Canons that prohibit prayer with (though assuredly not for) the non-Orthodox.
Now, admittedly, if we refuse to pray with the non-Orthodox, we appear—again because we are unable to address religious issues, today, with any depth—rude, if not downright sectarian. In view of this, probably the most prudent thing to do, when you are invited to a meal in a non-Orthodox household, is to stand (or sit) respectfully while your hosts pray as they see fit. Afterwards, before you eat, you can Cross yourself and silently recite the appropriate Orthodox prayer. Whatever you do, you must keep in mind that the canonical guidelines that prohibit us from praying with the non-Orthodox, based solely on the precepts discussed above, must never become an occasion for showing disrespect or disdain for others or for their religious traditions. The Holy Canons are designed to protect our Faith, as the criterion of Truth, from any vitiation by what is foreign to that fullness of Christianity that Orthodoxy is. But this desire to protect our traditions is not selfish; it is motivated by love for those outside Orthodoxy, the pristine Faith—preserved among us alone—to which we hope that they will one day turn, if they are truly searching for God. Just as a good chemist would be remiss, were he to endorse some superstitious procedure from the false science of alchemy, so we Orthodox must not endorse the spiritual practices of those outside the Church. However, just as a chemist need not ridicule an alchemist, but should try to bring him to a knowledge of the real science of chemistry, so we must not show disrespect for the heterodox, but attempt to educate them by our good example and civility.
There are, of course, Orthodox who, zealous without knowledge, would use the Holy Canons—which are not laws, but principles which should guide us in making decisions regarding delicate matters of Christian comportment—to justify their un-Christian hatred for the heterodox and for heretics. They would thus argue that we should not sit at the same table with heretics or non-Orthodox, forgetting that this canonical prescription is aimed at insuring that, by eating in public with unbelievers, we do not somehow give the impression that we endorse their error and thus bring scandal on others. In modern America, this is hardly a risk while having dinner with non-Orthodox friends. Unthinking people might also say that by listening to the prayers of non-Orthodox, we are technically praying with them. We must simply ignore such irrational rubbish for what it is. An advocate of such thinking once told us that, following the agape meal in his parish on Sundays, all left-over food was thrown away, rather than given to the poor, since it had been blessed by an Orthodox Priest. To do otherwise, in his view, would have meant throwing what was blessed to the dogs. One can only imagine what Christ, Who calls us to feed the poor (St. Luke 14:13), or St. Paul, who tells us to feed even our enemies (Romans 12:20), would have said of such a thought. Prudence and true zeal should lead us in our relationships to the heterodox at all times. Otherwise, our wisdom becomes foolish and anti-Christian.
+ + +
From Orthodox Tradition, vol. XIV, no. 4, pp. 24-25.
+ + +
Father Anthony Nelson once submitted these helpful words to an Orthodox email forum: "The stricture against joint prayer with heretics is that such prayer falsely legitimizes their prayer, it raises their heresy—which is an attack on Christ's Church—to a level of perceived equality with Orthodox Christianity. It is not praying with heretics to allow them to visit our services, to be gracious hosts, for them to pray with us—which instead exposes them to the Church and Her prayer, and the noetic effects that prayer has on the soul (and there are, of course, such negative effects on the right-believing who enter into prayerful communion with those who are not Orthodox). This is not a phoney or contrived distinction, either...it is real, and those who want to find ways to pray with their heterodox friends with contempt for the Canons forbidding it are the ones who are misusing the Canons because they are making up observances that are not there and trying to pawn them off as the teaching of extremists" (who, they say, teach that the Canons forbid the heterodox to pray with us, and other distortions).
For instance, we have some vegetarian Buddhists, and lactovarian Hindus in the mix, so that means you absolutely must have something for them, and that requires no cute little ham chunks in the salads (for example).
Quite regularly some Shi'ites show up (friends of the kids from down the street), so we have turkeybased salami to put on the home-made cheese pizza, and everyone likes that.
We've had large events here where there weren't more than 4 people who belonged to even the same world-religion level "brand", like Christian, Buddhist, Mormon, Hindu, Shinto, Jewish, Shi'ite, Sunni, and so forth, to say nothing of denominations within a broad class.
So, to answer the question about prayer with the heathen, even those who believe they possess the revealed Word of God, or at least a serious guidepost to that Word if God were to reveal Himself ~ what everybody does is get the prayers out of the way before dining.
It's also a very good idea in a remarkably mixed crowd to begin serving "snacks" of appropriate kosher/halal/vegetarian mix BEFORE any main servings, and this tends to screw everybody up on when and where to pray, so usually nothing anyone does focuses attention on them and their own traditions (or religious obligations).
When serving mondu filled with kimchi it's a very good practice to inform everyone that it's strictly vegetarian. Otherwise, virtually everyone assumes the kimchi is filled with roast pork and garlic. Jains don't eat garlic.