I think atheists sometimes have a one-dimensional extreme view of believers. I never was a believer really (though I tried to be a Quaker for a while). I am a Unitarian-Universalist for social reasons (one joking definition of UUs is "atheists with children" -- and I'd encourage atheists to consider if it might meet their needs).

Believers know very well that there have been no unambiguous miracles lately, that really horrible things happen in the world despite a presumably benevolent God, and that the evidence for God is indirect. I think very few lie on their deathbeds with unalloyed peace and calm with the absolute conviction that they're going to heaven.

They are also well aware that different factions even within Christianity reach different conclusions about what God wants them to do.

There's a reason that religious communities are always dealing with doubters and speak of the need for having faith (despite a dearth of evidence), and understand that faith gets weaker and stronger. I think most have thought about losing their faith and what it would mean.

I don't have any statistics to quote, but I bet the majority of believers have views that are nuanced at least to this degree.