Ninteenth century German author and statesman Johann Goethe said “Man is made by his belief.  As he believes, so he is “.   That is, the things you have trust, faith and confidence in define who you are.

This implies people without beliefs are undefined.  Further if you know what someone believes you can predict how they will behave.  You can anticipate their responses.

To a large degree my own interactions with others prove this to be true.  The caveat is assuming you can accurately assess others beliefs.

Purposeful misdirection is a very real technique people can employ to gain advantage.  For example, one  might protray a strong belief in justice while in practice behaving soley in favour of their own personal gain, regardless of fairness.

Followers

Often followers fall into the group of those with undefined beliefs.  In these cases what appear to be their own beliefs are in fact those of another they are copying.

It is often hard to distinguish followers from true believers but this group is a favorite of unscrupulous leaders.  The follower can be manipulated into professing the leaders beliefs, thus supporting a cause that defines not themselves, but rather the leader.

Reason to Believe

If nothing else motivates you, the critical reason to believe (in something) and acknowledge that belief internally is because your beliefs will define you.   To ensure personal accountability and ownership of your life you must believe.