Apostle

ਰਸੂਲ (a Perso-Arabic loanword shared with Punjabi Sufi and Christian usage) conveys an authorized, sent messenger. NEVER use ਗੁਰੂ: in Sikhism this title is reserved exclusively for the Ten Gurus and the Guru Granth Sahib as the eternal, living Guru. Applying it to Paul or the apostles is a serious category error, not a stylistic softening.