Devil's advocate here....why wasn't the daycare issue discussed BEFORE the baby was born??? Just a point to ponder. But since that is neither here nor there, you need to make a decision based on what is best for your family.
Most moms would prefer to stay home with their kids, but for others there is no choice. For those that say it's a selfish lifestyle choice is plain BS. Maybe for some, but I think the general working-mom population would disagree. Some moms also opt for their kids to attend daycares and there is nothing wrong or selfish about that either. Some moms are BETTER moms because they work outside the home.
Anyway, your husband is right about a child needing to be socialized. I'm not sure there is much socializing going on at 6 months, but definitly by a year they should be introduced to their peers. It will only strengthen their independence as well as teaching them to share and play nice.
Your child would also gain so much knowledge from being in a center. If chosen properly, a daycare/pre-school can give them a GREAT headstart for when they do start school. It won't be such a shock to their system if they have spent time away from you and learned to cope on their own. This is just my opinion based on my own experiences with some kids, and to quote one of my fave Mamasource people, no heads exploding please....I think kids who go to daycare are much more advanced socially/academically and better behaved then kids who stay home. Again, JUST MY OPINION.
As far as the germs are concerned, it's better to have their immunities built up before they enter school and daycare does just that. My daughter was sick off and on at her school her first year, but it's been like three years and my DD hasn't had any major colds/flu.
Something your hubby might not be aware of is how expensive infant care is. At my DD center, it is $945 a month. Now I don't know what kind of job you would get, but you'll have to figure out how much would be left over after paying that hefty bill each month.
In closing, I really think it's a personal family decision. What may be good for that family, might not be good for this family. There are positives and negatives that can be made on both sides of the issue. The trick is deciding which outweigh the other for your family. Good luck!