I will give them an undivided heart and put a new spirit in them; I will remove from them their heart of stone and give them a heart of flesh. Then they will follow my decrees and be careful to keep my laws. They will be my people, and I will be their God. Ezekiel 11:19-20.
It is easy to individualise these verses and make them say something that they are not saying. However much God may want it to be true of me, they do not carry the promise that my heart will be undivided and that I personally will be single-minded in my love for God. No; in the Hebrew “an undivided heart” is simply leb echad — “one heart” — and the promise is of a day when God’s people collectively will be of “one heart” — just as they were once when they chose David as their king (1 Chronicles 12:38 , same expression). Look at the repeated use of “they” and “them”.
And, indeed, these verses find the start of their fulfilment not long after the resurrection of Jesus when, on the Day of Pentecost, God poured out his Spirit on the believers, and continued to “put a new spirit” in them: “After they prayed, the place where they were meeting was shaken. And they were all filled with the Holy Spirit and spoke the word of God boldly. All the believers were one in heart and mind.” (Acts 4:32). The Greek is kardia mia … one heart; just like the leb echad of Ezekiel 11:19.
Clearly the new spirit and the one heart belong together. The Spirit is the one who unites believers. Paul speaks of this oneness that is born of the Spirit in his letter to the Ephesians: “Make every effort to keep the unity of the Spirit through the bond of peace. There is one body and one Spirit — just as you were called to one hope when you were called — one Lord, one faith, one baptism; one God and Father of all, who is over all and through all and in all.” (Ephesians 4:3-6).
Three times, after the Last Supper, Jesus prayed for his disciples “that they may be one” (John 17.11,21,22). And then he gave his Spirit so that it should be so. “For we were all baptized by one Spirit into one body — whether Jews or Greeks, slave or free —and we were all given the one Spirit to drink.” (1 Corinthians 12:13).
Keep me of one heart, Lord, with all my fellow believers – held in the unifying fellowship of your Holy Spirit. Amen.