In my first draft of a response to your question, my focus was on the inherent conflict in values that you felt and which I believed motivated you to ask this question – your question not really being whether to inherently give a wedding present or not but rather whether to do so given that you had already decided to make a statement in not going to the wedding. You obviously felt that it was inherently proper to give a present but wondered about the effect of this action on your previous stance. I saw in this desire to give a gift a recognition of the value of tolerance within our society – and from which we Jews have greatly benefited – which calls upon us to respect the right of individuals to make personal decisions of this nature even though we may disagree. So I saw your question in the broader sense of how one can balance a personal value stance on an issue with the value which you also accept of tolerance of another who acts in disagreement with this viewpoint.
While I still believe that this issue is still very much part of your question, upon further reflection I began to recognize that in providing what I believe to be a Torah response to your issue, beyond simply responding to the conflict in values that you experienced, it would be first important to actually also look at the singular issues in themselves. Should one attend an intermarriage? A similar question could be asked in regard to attending a wedding between two Jews where non-kosher food is served or attending a same-sex wedding. At issue is the involvement one should have in an event that inherently includes an expression of a position with which one disagrees. Does my attendance reflect some acceptance of this position? Is it thus proper for me to attend?
The matter of the gift raises similar questions but also touches upon the more private issue of how one is to relate to another’s personal feelings. Your nephew experienced a joyful event, from his perspective, and you wish to share in this joy. On this level, you do not necessarily see this as reflecting a public expression of your stance and thus wish to give a gift. The more inherent question, though, may be whether it is proper to still share in this joy. Is it right, thus, in any such circumstance to give a gift? This individual is still your nephew.
The conflict of values that you are experiencing is still clearly a major part of this issue and there is a challenge in balancing one’s views with tolerance and respect for an opposing viewpoint. The essential question, however, is how the Torah views the entire situation. How are we to view a Jew who acts contrary to our understanding of how a Jew should behave? How are we to act in response to such behaviour? What we may find is that the various value considerations that we must undertake in response to such questions may actually yield what could be perceived to be contradictory behaviour.
Our first obligation is to follow Jewish Law so our initial question may be whether there is any violation of Halacha in attending an intermarriage. I am not speaking at this time in regard to the impression that one would be giving through this attendance but simply whether it is wrong simply to attend in its own right. There is an important distinction between the two. In regard to the latter perspective, we are solely focused on the behaviour itself. In regard to the first perspective, we are focused on the perception of others. If we state that a behaviour is inherently wrong, than the answer that we should not undertake this behaviour is pretty straightforward. If, however, we state that the issue really concerns the perception of others, than the evaluation of this perception is of major significance in regard to answering this question of behaviour.
To illustrate this issue, we could ask whether it is wrong for a person to watch another Jew eat a ham sandwich. We are not discussing in any way assisting this Jew in the consumption of this sandwich; that would involve concerns for the prohibition of lifnei ever and the further Rabbinic edicts to not assist an individual in sinning (see Sefer HaChinuch, Mitzvah 232). Is there a problem with just being a spectator of a sinful action? It seems that there could be – that viewing something negative should be avoided – and there is also a concern for being in the company of sinful people but these are not absolute prohibitions but rather guides that must be considered in the greater context. (We could also ask the question of what exactly is the sin in the actual intermarriage wedding ceremony.) I would contend that you could not really say that it is absolutely forbidden to attend an intermarriage ceremony but that it should be something that someone should refrain from attending. The further question would then be the second part of this issue – the perception of others.
In this regard, there are actually two considerations that must be kept in mind. One is the perception, through attendance, that one is in agreement with what is occurring. This touches upon the issue of ma’arit ayin, of giving an impression about Jewish Law and one’s relationship to it that is negative. If people will assume, through attendance at an intermarriage that one is okay with it than this is a problem. It is a value not only to be observant of Jewish Law but also to be perceived as one who is so committed. So there is a concern in attending an intermarriage that you will be seen as one is believes it to be okay.
There is, however, also a duty of care in regard to other Jews, to assist in ensuring their observance and continued association with the Jewish world. This is found, in its simplest terms, in the command to rebuke other Jews if they act in violation of the law. See Sefer HaChinuch, Mitzvah 239. A more thorough study of this command would show, though, that the command is not simply to rebuke but to take steps that would draw people to observe the law – and, as such, to specifically not rebuke if that will have negative consequences. See, further, Rabbi Moshe Weinberger, Jewish Outreach. In this regard, there could even be an argument to attend an intermarriage if there is a concern that non-attendance would create a rift that would drive the Jewish member of the couple further away from the Jewish community. (This is actually a further concern when it is the woman who is the Jewish partner for at issue would also be any future children of the union.) It is within this perception that we would also be highly concerned with issues such as tolerance and respect for individual decision-making. Showing disrespect to another is clearly a way to drive someone away from having any interest in Torah. The ultimate concern is the long term effect, not solely the short term perception.
In conclusion, what we find is that situations such as these demand true analysis and sensitivity to all the issues involved. In the end, the proper behaviour may be contradictory in its various details – and as such it may be that not attending yet giving a gift was the proper final conclusion in regard to what to do. On one hand, you wish to show your allegiance to the Jewish world. On the other hand, you wish to show your love for your nephew, not just abstractly but to you nephew. Both of these objectives indeed have value and so determining what to do is essentially most complex.