The passage
      v29. Paul begins by establishing an important principle. The age that we are part of is a "critical time" in human history. Yes, it is "short", passing away, transient, although Paul is actually saying, "the time is critical", rather than "the time is short." This is the moment in human history when all people can come to know the living God in Christ. The importance of this fact impacts on how we view our world, including our marriage. The reason Paul mentions marriage is because in this chapter he is writing against those who are promoting asceticism: sexless marriage; separation of marriage partners; single people remaining unmarried. As far as Paul is concerned, either married or unmarried is not really the issue. Grasping the substance of this critical moment in time is what matters, rather than being engrossed in the world, being possessed by this age. So, life will go on for all of us, either married or unmarried, but our central focus in this journey must be Christ; we must focus on eternal verities.
      v30-31a. Again, Paul is not advocating some form of asceticism, some form of Stoic apathy. In fact, in Romans 12:15 he tells us to weep with those who weep and to rejoice with those who rejoice. Nor is he telling us to have no contact with the world, no dealings with the world, no buying or using, no possessing or commerce. His point is simple, he warns us not to be absorbed in the things of the world, to not be "engrossed in them" as if the world and all that is in it, is other than transient.
      v31b. Paul concludes with a profound observation. We should not be absorbed in the things of the world for they are "passing away." He may not actually be saying the world itself is passing away, although this is true, but rather that the fabric of human society has no permanence. Sensual desire, human fun and tragedy, commerce, politics.... all that we put so much weight on, has little substance or permanence. All are but shadows that flee in the night. All that is so precious to us of this age "passes like an actor leaving the stage." It is for this reason, as Martin Luther put it, we must "not sink too deeply into it either with love and desire or suffering and boredom, but should rather behave like guests."

Don't be engrossed in the world
      I lay in a hospital ward full of sick and dying people and it was then that my mortality pressed in on me. When we reach middle age we find ourselves feeling agitated, hemmed-in, afraid ...., but unable to explain why we feel so uneasy. The sharp edge of our mortality is often hidden from us, particularly within the sophistication of our affluent life-style. A hospital ward can rip away the vale before our eyes.
      A believer is no less affected by the shadow of death, and like the rest of humanity, can try to compensate by an over-reliance on "the things of this world." In our passage for study, Paul gives us a piece of straight advice, based on two substantial truths.
        i] First, "this is a critical time." In the sight of God, this particular moment in human history is a critical moment before the end of the age. In this moment, in and through the person of Jesus Christ, it is possible for all humanity to come to know the living God, know him and live with him for eternity. For those of us in the know, it is not a time to be diverted by the fleeting shadows of this age.
        ii] Second, "this world, in its present form, is passing away." The shape of human society, of family, politics, commerce, education, art, science... and all the accumulated debris of human endeavour, are but shadows, images without lasting substance. That is not to say they are evil. It is true that evil people use them for evil purposes and thus pollute them, but they are still good in themselves, the bounty of a loving Creator. Yet, in the end this age is but a shadow "passing away." We are but "a mist that appears for a little while and then vanishes", James 4:14.
      So, how should we handle this critical moment within which the things of this world are but a fleeting shadow? We should "use the things of this world, as if not engrossed in them." We should enjoy, appreciate and participate in the bounty of God's creation without being absorbed by it. C.K. Barrett translates the verse this way, we should use the world as if we "had no full use of it." Life is on loan to us. We cannot possess it and it can never become substantial or eternal for us. We may believe, as a media commentator once put it, that "the person with the most toys when they die wins", but in truth, there is no winning with shadows.
      The purpose of life is to come to know the living God and share eternal existence in his presence. This purpose is realized by trusting him for our salvation and seeking to grow in him through his word. This must be the central purpose of our life, rather than the gratification of our sensual self. Let us enjoy the bounty of God's creation without being absorbed by it.

v29
      touto de fhmi "what I mean" - but this I say. The sense is to underline a new point rather than explain a previous one, so, "Let me underling this truth brothers."
      oJ kairoV "the time" - Either, "chronological time", or "a specific quality of a particular period of time", Cullmann. The sense of this "particular time" is a time of opportunity as against the movement/passing of time.
      sunestelmenoV (sustellw) perf. part. + verb to-be "has been shortened" - wrapped up, limited. Periphrastic perfect. Possibly "shortened", if the time in question is chronological, "the Lord will soon come", CEV, or "limited", "special", if the time is qualitative. "Critical time", Theiselton; "this is a critical time."
      to loipon artic. adv. "from now on" - rest, remaining, finally / since, therefore, so, henceforth. The sense is probably inferential, "since that is so", Barclay, although "Since" should commence a new sentence.
      iJna + subj. - Imperatival use of hina with the subjunctive, an uncommon use. The time is "short / critical" so our priorities must be reevaluated. Paul is not implying that husbands should leave their wives, just that, in the present circumstances, there are things more important than marriage." "So let those who have wives live as though they have none", Moffatt.
      wJV mh "as if [they had] none" - as if not. A married person is to live as if not possessed by / engrossed in / absorbed by, their marriage, as if marriage (the world, which in its present form is passing away) has priority over eternal verities. Note the parallelism of mourn / rejoice and buy / use, indicating that the imperative probably applies equally to the unstated parallel, married / unmarried.

v30
      oiJ klaionteV (klaiw) pres. part. "those who mourn" - the ones weeping, crying. Note the reversal of Jesus' words, Lk.6:21b, 25b. Those who mourn, as with those who rejoice, should live as if their mourning and rejoicing were quite irrelevant when compared to eternal verities.
      kateconteV (katecw) pres. part. "to keep" - possessing. "As if not really owning what we have purchased", "as if on loan." "Those who buy, as though they did not own what they bought", TEV.