I've heard different points of view about Israel and Christianity
but what exactly is a christian's obligation to Israel?
Our obligation is to love and pray for any and all Jews, and love and pray for any and all non-Jews; because God is all-loving >
"if you love those who love you, what reward have you?" Jesus says in Matthew 5:46.
And our Apostle Paul says, "first of all" to pray for all people > 1 Timothy 2:1-4.
So, God desires for us to care for any and all Jews and any and all non-Jews, in His love praying for all. Love "hopes all things" (in 1 Corinthians 13:7).
This one preacher John Haggee says it's mandatory,
I have heard John Haggee preach. I think he is very clear how he believes God wants us Christians to support Israel.
But the Jewish Torah is clear how if the Jews in the time of Moses did not honor and obey God, then God would have Gentile enemies come and kick the Jews out of their promised land and all over the earth. And this is what happened. So, if Jews do not obey and honor God, then according to their own Torah they are not guaranteed safety and security in the land now called Israel. Also, to my knowledge, the present land occupied by Jews is not all the land which was promised by the LORD to them. So, they have not returned to all of what the Bible says is their promised land.
But, like I consider > I can see how the promise of the land does not apply to ones who are disobeying God. So, in case they are not honoring and obeying and openly proclaiming Jesus as the Messiah of Israel . . . they possibly are not guaranteed anything until and if they openly honor and obey the rule of Jesus as their Messiah.
And so, it is not enough to try to help Jews who are not obeying God. They need first to seek Jesus.
Even so > there have been Jews who have proclaimed Jesus who is our Messiah. And we Gentiles who are Christians have joined with the Jews who started the ministry and witness of the Gospel and the New Testament. So, already, we are with the Jews who are Christians. There is no way you can say we have replaced our Apostle Peter and our Apostle Paul who were Jews by background before they trusted in Jesus.
yet I hear other opinions that focuses on replacement theology. What's going on?
Christianity was started by Jesus who was a Jew in flesh and blood, and who used Peter and Paul who were Jews, to start the life and ministry of Christianity. So, no way have we Christian Gentiles replaced Jesus our Lord and Savior who was Jewish as a Human, and no way have we replaced our Apostles Paul and Peter who were Jews!!!!
But unbelieving Jews were broken away, and we Gentiles in Jesus were then grafted in where the refusing Jews were broken away.
And we in Jesus already own all the promised land >
1 Corinthians 3:21-22.
Therefore, I consider from this scripture > Jews who are saved along with us saved Gentiles already own the whole world, which includes the promised land. And so we need not fool ourselves into believing how worldly people make things look

Jerusalem already belongs to us, according to God's word; and if and when the LORD pleases for any of us to go to Jerusalem, have a good time . . . if and howsoever God pleases.
But before you get overly concerned about the present land-based Jerusalem, you might consider how it is written that there is the Jerusalem which is "above" "and which is the mother of us all" > please see Galatians 4:26. And consider all which God's word says in Revelation about the "New Jerusalem" > Revelation 3:12 (Jesus says), and Revelation 21:2-22.
By the way, Galatians 4:26 says the Jerusalem "above" is "free". I consider that the present Jerusalem on this earth is not truly free. In God's love, we are free of fear, for one thing, free of arguing and depending on military force and security.
"There is no fear in love; but perfect love casts out fear, because fear involves torment. But he who fears has not been made perfect in love." (1 John 4:18)
So, we need to first be giving our attention to how we in God's love can be truly free, and know that our "mother" "above" Jerusalem is "free". And no one can be truly free only by use of military and politics and controlling this world's evil people.
And . . . again . . . what does our Apostle Paul say we need to do . . . "first of all"?
1 Timothy 2:1-4.
So, we can expect our Bible knowledgeable and honest ministers to emphasize praying for any and all people . . . and therefore, not only calling great and much attention to the land of Israel. So, yes, of course, if Jews do not bless Abraham by honoring Jesus, then those Jews need our prayer; they do not need land, but they need to trust in Jesus, or else they are not blessing Abraham, and so they need prayer.
But it is good to do good to Jews who do not believe, because Jesus says to love our enemies. And be thankful for the Jews who have honored our Lord and Savior and who started the spreading of the Gospel so we now have heard of Jesus and trusted in Him for our salvation and we have become children of God along with the Jews who started spreading the Gospel. Those Jews who have blessed us with the Gospel are not being replaced by us, but we are family together with our Groom Jesus.