Should a Christian cast out his child he had before marriage?

My paster and his wife have been married for 20 years and have four children together. He has a previous child he had out of wedlock from a previous relationship whom he was never married to. He has had nothing to do with this child since he has been saved. He believes that because she is part of his sinful past that he should cast her out of his life. He believes he has been forgiven of his sins that being a part of her life is wrong and going against God's plans for him. I am on the fence about this and would like some guidance on how I should handle this situation as a Christian. I myself have a child who I conceived out of wedlock (My son is 5 and half and I have been married for almost 4 years to his father, we have been together for almost 7 years) I know it was wrong, but in my heart I know God has forgiven me and knows that my son has been a product of love. However, as a Christian I do not understand how a man of God can cast out a child of his own just because that child was conceived from sin. I know that as a Christian myself that I should not judge my pastor or any other person. but I have a hard time respecting a man who totally abandons his child, as this child did not ask to be born or ask to be treated this way. I know that God loves this child like any other child. May this man feels that as a pastor that if he was to welcome the child into his heart and home that others would look down on him. I find it very sad and prays for them all. Please help me find a way to understand all this. When ever he is questioned about this by non followers he replies with this quote from the bible "The child begotten out of wedlock or incest shall not enter into the congregation of the Lord; even to his tenth generation shall he not enter into the congregation of the Lord." Deuteronomy 23:2. I guess this quote can be taken out of context but he stands strong on believing the fact that because she was created out of sin she has no place in his life now that he has been saved. I just have a hard time believing that as a Christian this is the right path to follow. But if he was saved and the child was saved can't he or she enter the kingdom of heaven.