en_tn/1jn/01/10.md

we make him out to be a liar

It is implied that a person who claims to be without sin would be calling God a liar since he said that everyone is a sinner. Alternate translation: "it is the same as calling him a liar, because he said we have all sinned" (See: rc://en/ta/man/translate/figs-explicit)

his word is not in us

"Word" here is a metonym for "message." Obeying and honoring God's word is spoken of as if his word were inside the believers. Alternate translation: "we do not understand God's word nor obey what he says" (See: rc://en/ta/man/translate/figs-metaphor and rc://en/ta/man/translate/figs-metonymy)