Once people realize Yeshua is the promised messiah and savior of the world, first in their head, then in their heart, a sense of joy and urgency overcomes them to share the truth and good news of His redemption and salvation.

John 3:16-17
King James Version
16 For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.

17 For God sent not his Son into the world to condemn the world; but that the world through him might be saved.