The purpose of this thesis is to present the basis for the church to take an inclusive stance toward children out of wedlock through the study of children out of wedlock in the Old Testament texts. For this purpose, I dealt with ‘Mamzer’ in Deuteronomy 23:2, the narrative of Jephthah (Judges 11), the narrative of Tamar (Genesis 38), and Isaiah 56. In chapter 2, it was concluded that the mamzer of Deuteronomy 23:2 should be limited to a special term for a child born through incest. In Chapter 3, through the study of the Jephthah and Tamar narratives, it was found that male out-of-married men are viewed negatively by the family or community, but are not discriminated against legally or in terms of property with their legitimate children. In contrast, if a woman conceives a child out of wedlock, the law of Deuteronomy applies and she is sentenced to death. Due to the patriarchal culture of the Old Testament, there is a very big difference in the status, rights, and social perceptions of the husband's children out of wedlock and the wife's children out of wedlock. In chapter 4, I tried to read Deuteronomy 23 in the light of Isaiah 56. Here, the stranger symbolizes a group of people with innate limitations, and the eunuch symbolizes a group of people with limitations due to acquired actions or factors. The condition for their acceptance into the community of Jehovah is that they do justice and righteousness, and keep Jehovah's law, covenant, and sabbath. In other words, if you make a covenant with Jehovah and keep that covenant, you will be recognized as God's people and accepted into Jehovah's community. In conclusion, as the church is a New Testament community that has opened a new era, we should no longer view unwed mothers and children out of wedlock negatively, exclude them from the church, criticize them, or do anything that disadvantages them.