As to your question about the spiritual children of people who enter the Cause with some old ideas still clinging to them: everyone should study the Faith for himself, and just because a person’s Bahá’í teacher has some concept not strictly Bahá’í it does not stand to reason that the new believer must be saddled with it; old believers, as well as new, should constantly endeavor to grow more fully into the Bahá’í pattern of thought and of life. Each should receives the gift of faith for himself, and from then on is a Bahá’í in his own right, independent of his teacher.
(Shoghi Effendi, Lights of Guidance, p. 78)
Praise thou God that thou hast succeeded in becoming a teacher of young Bahá’ís, young trees of the Bahá Paradise, and at the same time art able to benefit the other children as well. According to the explicit divine Text, teaching the children is indispensable and obligatory. It followeth that teachers are servants of the Lord God, since they have arisen to perform this task, which is the same as worship. You must therefore offer praise with every breath, for you are educating your spiritual children. The spiritual father is greater than the physical one, for the latter bestoweth but this world’s life, whereas the former endoweth his child with life everlasting. This is why, in the Law of God, teachers are listed among the heirs. Now you in reality have acquired all these spiritual children free and gratis, and that is better than having physical children; for such children are not grateful to their fathers, since they feel that the father serveth them because he must—and therefore no matter what he doeth for them, they pay it no mind. Spiritual children, however, are always appreciative of their father’s loving kindness. This verily is out of the grace of thy Lord, the Beneficent.
(Shoghi Effendi, The Compilation of Compilations vol. I, p. 273-274)
What the Cause needs is such ardent and self-sacrificing servants and not lukewarm followers who are ready to reap the fruit but unwilling to take a part in winning that victory. Shoghi Effendi, therefore, hopes that you will endeavour to make of your spiritual children of the type Bahá’u’lláh sought to have and create not passive admirers but active servants of the New World Order.
(Shoghi Effendi, Lights of Guidance, p. 113)