TA: God’s special treatment of Israel shows: (1) He discriminates, (2) He is a segregationist, and (3) He shows partiality, which conflicts with Acts 10:34, Romans 2:11, Galatians 3:28, Ephesians 6:9 and 1 Peter 1:17, 1:16).
Ed: Why did God choose the nation of Israel to be His special people? Here are just three suggestions: firstly, He has the prerogative to do whatever He will
(Isaiah 45:9); second, because He was keeping the promise He made to their ancestors that He would bless their descendants (Deuteronomy 7:8); thirdly because in His wisdom He judged that it was more effective to work directly with a single nation, rather than the entire population of the world (Deuteronomy 4:6, Exodus 19:5–6).
There are numerous accounts of God dealing with Gentiles in the Old Testament, for example Reuel, Rahab, Ruth and Ebed-melech, but it was always by means of bringing them into contact with Israel. In the New Testament, the Gospel opens up to all nations (Luke 2:32, Acts 26:17–18). But it’s important to note that even in the New Testament, the nation of Israel is still God’s special people at the centre of His plan (John 4:22, Romans 11:17–24, Galatians 3:8–14).
So in answer to your points:
1. God certainly does discriminate between good and bad, right and wrong, clean and unclean. That’s a basic principle of the Law of Moses and the law of Christ. But I think you’re using the word ‘discriminate’ in its particular meaning of ‘to make an unjust or prejudicial distinction in the treatment of different categories of people, especially on the grounds of ethnicity, sex, age, or disability’.* God is not unjust or prejudicial, He always exercises righteousness and truth (Psalm 19:9).
2. A segregationist is ‘a person who supports the policy of enforced separation of different racial groups’.* God did command Israel to be separate from the nations around them (Deuteronomy 14:2, 18:9–14). But there was always the opportunity for people who wanted to leave their own cultures and come to God to do so.
3. God does not show partiality. He will accept anyone who wants to come to Him, whether Jew or Gentile, but it must be on His terms. The verses you cite show this:
Acts 10:34–35—God accepts people from all nations, but they must fear him and do what is right.
Romans 2:10–11—God accepts people from all nations, but they must do good, and it’s the Jew first then the Gentile.
Galatians 3:26-29—those who are baptised become ‘Abraham’s offspring’ —spiritual Jews. When they are in this state, they are all of equal value to God.
Ephesians 6:9—Christ’s impartiality demands that we are impartial in our treatment of one another.
1 Peter 1:15–17—God will judge everyone impartially, but this means that we need to respond by striving for holiness.
*These definitions are from Oxford Languages via Google.