Andreas Kostenberger has a thoughtful post on singleness in the Bible. I especially found one observation noteworthy. He finds a trajectory across salvation history with regard to singleness and marriage. Marriage is part of the creation order, part of God's original intent before the fall. It isn't until Jesus comes along to initiate the new covenant that you get any sense at all that there's anything but marriage as the norm, with singleness as an extraordinary exception (e.g. widows, serious illness). But Jesus indicates that some will be single by choice, and Paul even argues that the kingdom is more greatly served (in certain kinds of situations?) by those who are single, and therefore what was once the exception becomes something especially useful.
But Jesus also indicates that there will be no marriage in the resurrection. That means the intermediate phase between the initiation of the new covenant and its ultimate fulfillment in the resurrection is in tension between the marriage norm of the old covenant and the singleness norm of the resurrection. Seeing this according to a trajectory makes so much sense of how Paul can have such a high view of marriage and yet also view singleness as something for some to strive for. This doesn't (as some have argued) imply a lower view of marriage but simply reflects the tension between these two norms, one eventually to be replaced by the other but both having value in the in-between time. But Kostenberger does take marriage as a sort of norm even in this age, citing Matthew 19 as evidence. It's just not a norm in the fuller sense of when most everyone would be expected to get married.
One thing that occurred to me while reading his post is that there's an ambiguity in the expression 'the gift of singleness'. I think I've now come to think of that expression as referring to at least two different things, and people often use it without thinking of both senses. One gift of singleness is someone's being especially gifted by God to be better suited for a life of celibacy. Paul does seem to speak of some who are gifted to singleness in this way. He speaks of those who would burn as not enabled in this way. There's some debate among scholars about whether that simply means burning with passion or if instead it is about burning in hell for not being able to maintain faithfulness to God because of sexual desires, but either way there seems to be a distinction between people especially gifted in what not being married requires.
At the same time, Paul seems to me to speak of singleness itself as a gift. This is a gift possessed by everyone who is single. Everyone has this gift at some time, of course, but some people have it longer than others, and some have it their whole life. Some have it after having been married for a time. The fact that someone is single allows for kinds of ministry that are not possible or much more difficult for married people to engage in. That is indeed a gift, and as it's a means of God's grace I can't see why it shouldn't be counted as a spiritual gift.
A third meaning of 'the gift of singleness' might be what Kostenberger calls the calling to be single. Since a calling in the NT is usually just something all believers are called to, I don't like using that term for some specific task or purpose God has assigned to an individual, but I'll let that slide for the purposes of this post. The calling to singleness in this sense seems to be something other than the special strengthening to be single that some people have, and it also seems distinct from merely being single. Now it may be that in many cases all three go together, but that doesn't seem to me to be true of some cases, and people might mean any of these three when they speak of the gift of singleness. All three count as gifts, and they are not the same gift as each other.
A lot more can be said about this issue of course, but this was what occurred to me as I was reading Kostenberger's post. Speaking of his post, have you gotten this far in my post without reading his? If so, what are you waiting for? Go read it.