A Just because you don't drink alcohol doesn't mean you have to miss out on team nights out. You are more likely to be conspicuous by your absence than you are by avoiding alcohol. So, for example, why not join your colleagues for a drink, but stick to something soft? Also, make sure you take your turn to buy drinks - it shows involvement and also affords you the opportunity to be subtle about your choice of drink. What matters is that you are seen to be part of the team by joining in with the banter, the discussions and sharing information.
You also don't need to attend every night out. Don't always make an excuse, but if you have plausible reasons for missing some after-work drinks they are unlikely to think less of you. It's only if you constantly avoid them that they will begin to question your motives.
The other thing to consider is whether a night out drinking is the only option. Why don't you suggest something else as an alternative? Would going out to a restaurant be an option? In other words, make sure you are seen to be coming up with ideas for socialising with your colleagues. By doing so they will see that you are keen to participate. Some may even welcome alternative ideas - but are looking for someone else to take the lead.