信じる
しんじる · shinjiru · JLPT N3 · verb-ichidan
to believe
信 = person 亻 + words 言: trusting a person's word
The kanji 信 joins 亻 (person) and 言 (speech): someone standing by what they say. Add じる to make the verb, to believe. The same 信 appears in 信用 (trust) and 自信 (self-confidence), so shin carries the sense of trust across many words.
信 — person 亻 + speech 言
信 combines 亻(person) with 言(speech), depicting a person standing by their words. The original sense is 'truthfulness' or 'sincerity'—what a person says can be trusted. From this it extended to 'believe,' 'trust,' and later 'message' or 'letter,' since a letter carries one's word.