There are a couple of issues here to consider; one is the concept of creating a life form artificially, and the other is how it's being done.
Regarding the concept, there may be a wide variety of viewpoints and several arguments that both support and oppose the concept. These include (not an exhaustive list):
- When God created the world, and all living things in it, what he created was perfect. Therefore to add to that perfect creation would be a move away from perfection, and thus wrong.
- Creating life is God's job. By taking on this role we are setting ourselves up as gods, which is a direct violation of some of the key directions that God has given us - most famously, "No other gods, only me" from the Ten Commandments (Exodus 20:3)
- When God created mankind, he gave us all the knowledge and intellect that we have. (The one piece of knowledge he didn't give us, but we took for ourselves, is the knowledge of good and evil). Thus our ability to artificially create simple "life forms" is not inherently a bad thing. You could liken it to developing breeds of cattle or dogs, or cross-fertilizing plants to create new varieties, and argue it's just an extension of that kind of activity.
- God gave mankind dominion over all other life on the Earth, and told us to take charge of and be responsible for all living things. Therefore there's nothing immoral about our creating new forms of life from existing forms of life; God has granted us that right (and also told us to use it responsibly).
Speaking personally I know of very few Christians who object to the concept of creating a living thing artificially.
The practice may throw up some other considerations though, especially if the "raw materials" being used come from human embryos. I'm sure you're already aware of most of the arguments about embryo-related research so I won't repeat them here - particularly as the example you cited in the question doesn't go near human embryos, but is inserting a completely synthetic genome into a bacterium. It's worth noting that the critics in that article were "including some religious groups" - there's nothing to suggest that the views those critics expressed represented all, or even a majority, of Christians.
Some further reading that may be of interest: