Just aghast at people who believe they are 'following' Jesus by singing songs, going to church, studying theology, etc.
The point of Jesus' call is to imitate him - mystically, symbolically, socially and pragmatically.
The biblical idea commonly translated as believe is corrupted if people think it is just intellectual assent to unprovable ontological statements about Jesus. The word implies a commitment to living out the values of a community.
To that extent - while I would not presume to make an eschatological principle out of this - I am not sure that non-'Christians' whose behaviour reveals a Christic principle are not better followers of Jesus than some whose discipleship stops at noisily proclaiming that He is co-eternal with God and died for their sins.
Belief certainly starts with certain cosmological and epistemological assumptions, but becomes real when it becomes existentially real through one's decisions and choices.