That verse doesn't necessarily mean that the spirit is gender-less. It refers specifically to lust (that is, sexual activity outside of marriage). If you wanted to get a better reference, go for "they will be like the angels of God in heaven, neither married nor given in marriage." Yet even that doesn't necessarily convey a lack of gender, but merely how procreation (and thus, marriage as an institute for child-raising) are not needed in eternity. I'm not saying that people's souls have genders (although I do think men and women have different psychological natures), but I am saying that, to the best of my knowledge, the Bible does not explicitly teach that the spirit is without gender