An important matter for Muslims to realize is that Da’wah is an obligation upon them. Allah says in the Qur’an:
Invite to the Way of your Lord (i.e. Islam) with wisdom and fair preaching, and argue with them in a way that is better. Truly, your Lord knows best who has gone astray from His Path, and He is the Best Aware of those who are guided.” (Qur’an, 16:125)

Let there arise out of you a group of people inviting to all that is good, enjoining Al-Ma’roof (i.e. Islamic Monotheism and all that Islam orders one to do) and forbidding Al-Munkar (polytheism and disbelief and all that Islam has forbidden). And it is they who are successful.” (Qur’an, 3:104)

Prophet Muhammad (peace be upon him) said: “Convey from me, even if it be one verse.” (Al-Bukhari)

Conveying the message, therefore, is the responsibility of each and every Muslim, according to his or her ability. Yet, this Da’wah should be based on knowledge and practice. One cannot call people to Islam without knowing what Islam is and acting upon it in the first place.

The obligation is further emphasized by the following verse which explains that not conveying the message and hiding knowledge is disobedience to Allah that causes Allah’s curse to descend upon such people.

Verily, those who conceal the clear proofs, evidence, and guidance, which We have sent down after We have made it clear for the people in the Book, they are the ones cursed by Allah and cursed by the cursers.” (Qur’an, 2:159)

In the same connection, the Prophet (peace be upon him) has stated, “Whoever hides knowledge, Allah will brand him with the branding iron from the hellfire.” (Ahmad)

Calling people to Allah also means completing our own worship, the reason for which we are created. It is one of the noblest acts that entails a high reward.

And who is better in speech than he who invites to Allah and does righteous deeds, and says: ‘I am one of the Muslims.’” (Qur’an, 41:33)

With regards to the reward, the Prophet (peace be upon him) has said: “Whoever guides (another) to a good deed will get a reward similar to the one who performs it.” (Sahih Muslim)

Also, “By Allah, if Allah were to guide one man through you it would be better for you than the best type of camels.” (Al-Bukhari and Muslim)