Clearly, 'giveth' refers to sexuality, thus when Luke and Paul and Matthew and Mark refer to this 'giving in marriage' they are referring not to a ceremonial ritual but to the sexual intimacy of marriage which is precisely what Jesus instructed would not be a part of the resurrection or Heaven! To teach otherwise in order to institute plural marriage is heresy. To teach that there will be 'creating of spirit children by those married who were sealed in Mormon temples on earth' is teaching heresy.
We’ve discussed this concept before. You seem stuck on the notion that creation of spiritual offspring means sex. It may, it may not. I haven’t asked God about His sex life, so I don’t know exactly what processes are involved in bringing a spiritual child, such as your and my souls, into existence. I would assume some sort of organizing process whereby raw material is formed into sentience, but the topic is mostly outside the scope of LDS doctrine.
Nevertheless, our detractors often say that the LDS Church teaches that God has some kind of sexual relationship with His goddess(es) in order to produce spiritual offspring. The LDS Church does -not- teach this. Therefore, your accusation of heresy on these grounds is not justified.
We -do- believe that the marriage relationship can be codified in the hereafter and last into eternity. This is done through a priesthood ordinance known as “sealing,” and it may be performed vicariously for couples who are dead. However, to the best of my understanding, the LDS Church does not teach that people get married in the afterlife. Therefore, yet another accusation of heresy from you is unwarranted.
Please, learn our doctrine before you try to marginalize us with it.