I believe that if the god of Christianity exists then the bible is a guideline for the moral dos and don'ts. From what I have read of the bible, there is nothing written in it that forbids creating custom test-tube babies. I believe that if God didn't want us to do this, it would have been written in the bible.
Yes,I think bGod supports humans creating custom test-tube babies.Since God gave humans the technology of test-tube babies,it would just make sense that God approves of test tube technology.He knew there were people out there that could not conceive in any other way and wanted to give them the chance to become parents.
There is no such thing as God, no matter how hard you want him to exist. There is no proof of it. Therefore your argument about test-tube babies only has ethical issues,not religious. The quicker we get rid of these notions, the quicker we can evolve on to a new plain of science.
I personally think that God probably does not support humans creating a custom test tube for babies unless it is to help the babies breathe. I personally think that God probably does not support humans creating a custom test tube for babies unless it is because it is for the babies safety.
God would not support humans attempting to make custom test tube babies. This could lead to the slippery slope of humans making designer babies and getting rid of babies that are not desirable. Adolph Hitler would of believed in making custom test tube babies and he attempted to do just that.