Only those whom God foreknew equates to Israel or Jews of faith, who like Paul are his kinsmen according to faith. First Paul asks a rhetorical question "Has God cast away His people"? Paul basically says of course not because even I am an Israelite of the seed of Abraham and the tribe of Benjamin. Clearly then God has not cast away all of them! Paul proves this in greater depth when he says God has reserved 7000 from Israel of old who have not bowed to Baal, or Jews of faith. Therefore, at the present time God has reserved from Israel a remnant according to election of grace.
When Paul said he was of the seed of Abraham he wasn't limiting the seed to Israel of the flesh, even though it is true Paul was indeed a Jew according to the flesh. But the seed that God foreknew does not speak of the natural seed (many) of Abraham, but of the spiritual Seed (Christ) that came through Abraham. Because you cannot say ethnic Israel in unbelief are of those whom God foreknew. Because to be among those whom God foreknew is to be conformed to the image of Christ. Clearly, unbelieving ethnic Israelites of old were not conformed to the image of Christ.
Romans 8:29 (KJV) For whom he did foreknow, he also did predestinate to be conformed to the image of his Son, that he might be the firstborn among many brethren.
Romans 11:4-5 (KJV) But what saith the answer of God unto him? I have reserved to myself seven thousand men, who have not bowed the knee to the image of Baal. Even so then at this present time also there is a remnant according to the election of grace.
Romans 11 is not a problem for Amill or any other doctrinal position when one understands the difference between the Seed (Christ) of Abraham whom God foreknew, and the seed (as many natural descendants) never foreknown of God. According to Paul there is from Israel only 7000 (remnant) from Old Covenant Israel reserved by God, even in his lifetime Paul says there was only a remnant according to the election of grace.
Christ had declared Himself as the promised Messiah that was to come. But those of His own ethnicity who were first to receive the message of salvation through Christ denied and rejected Him. Even the many miracles He performed which should have convinced them He was the promised one to come, they accused Him of doing these miracles under the power of the Devil. So, those who would have been first to enter, did not enter because of unbelief. Having been cast out through unbelief the Gospel is sent unto the Gentiles, who are no longer last to enter the Kingdom, and through the Gentiles proclaiming the Gospel to unbelieving Jews they too can be grafted in again IF they do not remain in unbelief.
Luke 13:23-30 (KJV) Then said one unto him, Lord, are there few that be saved? And he said unto them, Strive to enter in at the strait gate: for many, I say unto you, will seek to enter in, and shall not be able. When once the master of the house is risen up, and hath shut to the door, and ye begin to stand without, and to knock at the door, saying, Lord, Lord, open unto us; and he shall answer and say unto you, I know you not whence ye are: Then shall ye begin to say, We have eaten and drunk in thy presence, and thou hast taught in our streets. But he shall say, I tell you, I know you not whence ye are; depart from me, all ye workers of iniquity. There shall be weeping and gnashing of teeth, when ye shall see Abraham, and Isaac, and Jacob, and all the prophets, in the kingdom of God, and you yourselves thrust out. And they shall come from the east, and from the west, and from the north, and from the south, and shall sit down in the kingdom of God. And, behold, there are last which shall be first, and there are first which shall be last.
Therefore, many are called by the Gospel message that all people of the earth can now hear. But only those chosen for eternal life will according to grace through faith hear the Gospel by the power of the Holy Spirit and believe to the saving of their soul.
I'm beginning to wonder if you have any real understanding of Amill doctrine at all? When using the term ethnic Israel, we are making a distinction between Israel of faith and Israel in unbelief. All are Jews, but only Jews of faith belong to Israel of God. Ethnic Israel of the seed (many) of Abraham is NOT the true Israel of God. Have you not read what Paul says regarding the ethnic Jews in unbelief?
Romans 9:2-8 (KJV) That I have great heaviness and continual sorrow in my heart. For I could wish that myself were accursed from Christ for my brethren, my kinsmen according to the flesh: Who are Israelites; to whom pertaineth the adoption, and the glory, and the covenants, and the giving of the law, and the service of God, and the promises; Whose are the fathers, and of whom as concerning the flesh Christ came, who is over all, God blessed for ever. Amen. Not as though the word of God hath taken none effect. For they are not all Israel, which are of Israel: Neither, because they are the seed of Abraham, are they all children: but, In Isaac shall thy seed be called. That is, They which are the children of the flesh, these are not the children of God: but the children of the promise are counted for the seed.
As you can see, it is possible to be of the seed (natural/many) of Abraham, according to the flesh, but in Isaac shall thy seed (Christ) be called. They who are of the flesh (Abraham's natural seeds) are NOT the children of God. For natural/ethnic Israel to be children of the promise (the Seed/Christ) they must also be of the seed (Christ) through/in Isaac. Because Christ came through the seed of Abraham, Isaac and Jacob. Therefore, Jews who profess only to be of the seed (many/ethnic) of Abraham are not the seed (Christ) of promise.
It was a source of great pride for ethnic Jews to profess Abraham as their father. They believed that having Abraham made them secure in God. They thought lineage would save them, and Orthodox Jews in Israel today still believe this.
God made a Covenant of land with Israel of old. The promise was that they would inherit the land of Canaan, the Promised Land eternally IF they remained faithful to God and did not break the Covenant. In His written Word God gives us assurance that all the promises He made with Israel of Old have been fulfilled. Nothing of what God promised them has not been fulfilled. But the people of Israel were not faithful to the Covenant so just as God promised they forfeit the Promised Land.
Joshua 21:43-45 (KJV) And the LORD gave unto Israel all the land which he sware to give unto their fathers; and they possessed it, and dwelt therein. And the LORD gave them rest round about, according to all that he sware unto their fathers: and there stood not a man of all their enemies before them; the LORD delivered all their enemies into their hand. There failed not ought of any good thing which the LORD had spoken unto the house of Israel; all came to pass.
Joshua 23:11-16 (KJV) Take good heed therefore unto yourselves, that ye love the LORD your God. Else if ye do in any wise go back, and cleave unto the remnant of these nations, even these that remain among you, and shall make marriages with them, and go in unto them, and they to you: Know for a certainty that the LORD your God will no more drive out any of these nations from before you; but they shall be snares and traps unto you, and scourges in your sides, and thorns in your eyes, until ye perish from off this good land which the LORD your God hath given you. And, behold, this day I am going the way of all the earth: and ye know in all your hearts and in all your souls, that not one thing hath failed of all the good things which the LORD your God spake concerning you; all are come to pass unto you, and not one thing hath failed thereof. Therefore it shall come to pass, that as all good things are come upon you, which the LORD your God promised you; so shall the LORD bring upon you all evil things, until he have destroyed you from off this good land which the LORD your God hath given you. When ye have transgressed the covenant of the LORD your God, which he commanded you, and have gone and served other gods, and bowed yourselves to them; then shall the anger of the LORD be kindled against you, and ye shall perish quickly from off the good land which he hath given unto you.
Salvation has come to the Gentiles through the fall of Israel. Now through the Gentiles and Jewish Christians, ethnic Israel or Jews in unbelief can still be saved by grace through faith if they do not remain in unbelief when they hear the Gospel and believe Christ. There is no more a distinction between Jews and Gentiles for in Christ there are only those who are of faith Christians, and those who remain in unbelief the lost.