Am I obligated to invite and advise some people who are not from the Sunnah, by sending some tapes and booklets?

Inviting the people of innovation (Ahl al-Bid'a) to the Sunnah is one of the most important objectives of the religion. It falls under enjoining what is right and forbidding what is wrong.

It is obligatory to invite the people of innovation and explain the Sunnah to them, as long as no harm results from it. However, it is important to note that speaking with them requires deep-rooted knowledge to dispel misconceptions. Otherwise, it is better to avoid speaking with them, because warding off harm takes precedence over achieving a benefit, and because misconceptions can affect the heart.