xin4 is made up of where the first component is ren2 which means 'man' (a stick figure of a walking person but when used as a Bushou as is the case here, it is always tilted 45 degrees) and the second is yan which means 'word' or 'speech' (a hieroglyph that depicts the tongue protruding from the mouth - bottom square). A man who abides by his word is believable.
xin4xin1 means 'faith' and literally translates as 'believe'-'heart'.
xin1 is a hieroglyph of the heart .
xin4ren4 means 'trust' and literally translates as 'believe'-'allow'.
has two components
where the first has been explained above and the second is ren
which has the connotation of 'come what may'. To accept another person's
decision is to 'allow' (sometimes with resignation).