Will I be sinful if I do not lead people in prayer, after being prevented by the Endowments Ministry from teaching, preaching, and delivering sermons, even though some have asked me to intercede with the Endowments Ministry and promise not to delve into certain religious issues?

There is no sin upon you for not leading people in prayer (imamah) or for not delivering sermons and lessons. However, if there is a greater benefit in giving lessons, then you should be keen on doing so. Continue enjoining good and forbidding evil through advice and clarification, and by deterring people from transgressions to the best of your ability.