For me it is a matter of priorities. I was raised in a very religious family and attended a christian school half of my life. We always knew that church attendance was expected on Sunday morning (just like school or work on Monday morning) and activities were adjusted accordingly.
I still try to make church a priority and we are very active in the Presbyterian church. We do miss occaisionally for important events-our local sprint triathlon series is on Sundays-but we try to attend Sunday night instead.
In the summer, we ride on Saturday mornings and run before church on Sundays and this schedule works with our riding buddies. We attend a larger church that offers 3 services on Sunday morning and 1 on Sunday night, so there are more options (although 8:15 AM is perfect for us!).