Here are some thoughts on working together with other Christians...
I had the opportunity to speak with student workers in my wider church family (Newfrontiers) about how to work with Christian Unions (my day job).
It was wonderfully encouraging to develop relationships and share in mission together to see the local church built.
How can things work more smoothly? (which applies to any local or trans-local relationship, of which UCCF and CUs with local churches are an example.)
1. Be generous. Get the point that the gospel makes us generous spirited people. I'll think and speak generously, rejoice when someone else is blessed more than me. That means I can look past and even rejoice in some of our differences - whether in class, culture, and even some convictions... There are theological differences that can stop people working together, but there are probably fewer than we normally think... inevitably we all get used to the air we breathe and start to think that our way is the only way... the only antidotes to this are to go deep with the gospel and to commit to mixing widely with other lovers of the gospel. This is something I value about the DNA of the UCCF, gospel depth and breadth.
2. Be a blessing. Look at your ministry and ask yourself, what can I give away for free to others. And do it without caveats and conditions. Where can I open my doors? Where can I invite others to join us with something we're doing? I've tried to invite people into things we're already doing, and I've tried to create contexts that are suitable to invite people into.
3. Be a learner. Look at your ministry and at others, and ask: what do we need to learn from others, and invite them to come and teach you out of their strength. Every church and movement has its weaknesses, and its almost certain that someone in your town is strong where you're weak. I've found Terry Virgo to be a great example of this, happily inviting a Rob Rufus and Mark Driscoll to speak at Newfrontiers leaders conference... Sure he'd disagree with some of what both say and believe, in their theology/methodology, but the more mature the people in the room the less chance anyone is being confused, and we might just learn from where others are doing better than us.
4. Be hospitable. You can't be best buddies with everyone in the area but you can be good friends with some people. Call up someone else, invite them over and get to know them. It's the easiest thing and one of the most magnificient things someone can do... let's eat, enjoy friendship around a table - let's really meet.
The point here is Holy Spirit unity expressed in real relationships, not power play for political advantages, it's about service and giving rather than winning.
In all of this the only valid "parachurch" is ministry that exists is rooted in local churches and which exists for the good of the local churches - we can all be part of local and trans-local relationships between churches which may prosper others more than they prosper us - but if Paul can rejoice when God prospers the ministry of ill-motived people, then we can probably rejoice when no one is having to question motives.
Remember: Gospel. Remember: Relationships.
See also: Parachurch that loves the local church and Parachurch and the Emporers New Clothes