I am always fascinated by answers to this question, because they are usually as diverse and wide-ranging as the people who make up a church! This is a definition of church written by Eugene Peterson in his commentary on Ephesians (‘Practise Resurrection’):

“Church is an appointed gathering of named people in particular places who practise a life of resurrection in a world in which death gets the biggest headlines… The practice of resurrection is an intentional, deliberate decision to believe and participate in resurrection life, life out of death, life that trumps death, life that is the last word, Jesus life.” (Eugene Peterson, ‘Practise Resurrection’, P 12)

He goes on to say this is worked out in:
1) the worship of God in all the operations of the Trinity
2) the acceptance of a resurrection, born-from-above identity (identified in baptism)
3) the embrace of resurrection formation by eating and drinking Christ’s resurrection body and blood (at the Lord’s Table)
4) attentive reading of and obedience to the revelation of God in the Scriptures
5) prayer that cultivates an intimacy with realities that are inaccessible to our senses
6) confession and forgiveness of sins
7) working and speaking for peace and justice, healing and truth, sanctity and beauty
8) care for all the stuff of creation.

What’s your definition of ‘church’?