Changing demographics and attitudes necessitates changing definitions related to those to attend and avoid church.
From the Barna Research Group:
New Statistics on Church Attendance and Avoidance

New Measures
According to Barna, one way of examining people’s participation in faith communities is by exploring how they practice their corporate faith engagement. Unveiling a new measurement model, Barna identified the following five segments:
+ Unattached – people who had attended neither a conventional church nor an organic faith community (e.g., house church, simple church, intentional community) during the past year. Some of these people use religious media, but they have had no personal interaction with a regularly-convened faith community. This segment represents one out of every four adults (23%) in America. About one-third of the segment was people who have never attended a church at any time in their life.
+ Intermittents – these adults are essentially “under-churched” – i.e., people who have participated in either a conventional church or an organic faith community within the past year, but not during the past month. Such people constitute about one out of every seven adults (15%). About two-thirds of this group had attended at least one church event at some time within the past six months.
+ Homebodies – people who had not attended a conventional church during the past month, but had attended a meeting of a house church (3%).
– adults who had attended both a conventional church and a house church during the past month. Most of these people attend a conventional church as their primary church, but many are experimenting with new forms of faith community. In total, Blenders represent 3% of the adult population.
+ Conventionals – adults who had attended a conventional church (i.e., a congregational-style, local church) during the past month but had not attended a house church. Almost three out of every five adults (56%) fit this description. This participation includes attending any of a wide variety of conventional-church events, such as weekend services, mid-week services, special events, or church-based classes.
Cross-Pollinating the Church
In addition to those five segments, the Barna report revealed that there is a growing degree of ministry crossover in America. When examining the spiritual participation of adults during the past month, the Barna team discovered that more than one out of every five adults had been involved in two or more types of churches: a conventional church, a house church, a marketplace church, a real-time ministry event on the Internet, or a live ministry event in the community.
Demonstrating the complexity of measuring people’s faith commitments, the Barna study identified the nature of people’s overlapping faith practices.
+ Among adults who were churched (either conventionally or alternatively) 15% had experienced the presence of God or expressed their faith in God through a faith-oriented website within the past month. Half as many (7%) said they had such an experience through a real-time event on the Internet.
+ One out of every eight churched adults (13%) said they had experienced the presence of God or expressed their faith in God through a ministry that met in the marketplace (e.g., their workplace, athletic event, etc.) during the past month.
+ Twice as many churched people (28%) said they had experienced the presence of God or expressed their faith in God through their involvement with a special ministry event (such as a worship concert or community service activity).
+ A majority of the public claimed to have experienced the presence of God or expressed their faith in God through some form of interaction with religious television or radio programs.
Reaching the Unattached
With the final weeks of the Easter season rapidly approaching, the Barna study also identified some of the characteristics of the Unattached that might enable conventional churches or other ministries to more adeptly connect with those people.
Compared to regular churchgoers, the Unattached are:
# more likely to feel stressed out
# less likely to be concerned about the moral condition of the nation
# much less likely to believe that they are making a positive difference in the world
# less optimistic about the future
# far less likely to believe that the Bible is totally accurate in its principles
# substantially more likely to believe that Satan and the Holy Spirit are symbolic figures, but are not real
# more likely to believe that Jesus Christ sinned while He was on earth
# much more likely to believe that the holy literature of the major faiths all teach the same principles even though they use different stories
# less likely to believe that a person can be under demonic influence
# more likely to describe their sociopolitical views as “mostly liberal” than “mostly conservative”

The entire article is worth a read.