How can one have an “effect upon the hearts” of others so they become attracted to “the Kingdom of God”

O maid-servant of God! Forget all else save God, be in communion with Him, supplicate and pray to Him to make thee conqueror over the material things, impressed by the bounties of the Kingdom, commemorating the name of thy Lord, pure from all else save Him, and imbued with the spiritual attributes of those who are holy (and high); then shall thy breaths have effect upon the hearts, and attract the hearts of thy son and husband unto the Kingdom of God. (‘Abdu'l-Baha, Tablets of Abdu'l-Baha v2, p. 246)