Either intentionally taking an innocent human life is right or it is wrong.
Opposition to the intentional taking of an innocent human life is simply the right position.
Fanaticism has nothing to do with it.
IVF, itself, does not intentionally take an innocent human life any more than conventional attempts at getting pregnant frequently do, especially among the same risk class of person who would seek IVF. Why is it worse for a person to fertilize 20 embryos and only have one child than it is to have 7 miscarriages and an unspecified number of eggs that were fertilized but never implanted trying to get pregnant naturally to have one child, especially if one considers even blocking contraception like a condom a sin, too? In neither case is a person intentionally taking an innocent life, even though children are lost.
It's not IVF that's the problem. It's the abuse of IVF and the careless destruction of embryos that's the problem (and Coleus is absolutely right to shine a moral light on that). But there are people who can and do practice IVF responsibly, with due consideration placed on giving every embryo created a chance to be born, but there are also far more people who simply destroy the embryos that they don't want once they have the children they do want. It's that abuse and willing destruction of embryos that's the more constructive target of criticism than people who simply need help having a child and use every embryo that's created.