16:125 - Invite (all) to the Way of thy Lord with wisdom and beautiful preaching; and argue with them in ways that are best and most gracious: for thy Lord knoweth best, who have strayed from His Path, and who receive guidance.

103:1-3 - By (the token of) time (through the ages); verily man is in loss, except such as have faith, and do righteous deeds, and (join together) in the mutual teaching of truth, and of patience and constancy.

The Prophet has said "Convey from me, even one verse" [al-Bukharee]. Conveying the message does not even require a complete knowledge of Islam. It is however a responsibility that one must convey the message to his or her ability.
Allah (SWT) has also promised great reward in fulfilling this obligation of dawah. 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 entail a high reward.

41:33 - And who is better in speech than he who invites to Allah and does righteous deeds, and says: 'I am one of the Muslims

2:159-160 - Those who conceal the clear (Signs) We have sent down, and the Guidance, after We have made it clear for the people in the Book, -on them shall be Allah's curse, and the curse of those entitled to curse,- except those who repent and make amends and openly declare (the Truth): To them I turn; for I am Oft-returning, Most Merciful.

Regarding the same, the Prophet has stated, "Whoever hides knowledge, Allah will brand him with the branding iron from the hellfire." [Ahmad]