They need a spiritual tradition through which to experience lifecycle events, and to have a community where they feel at home.
And if the spouse has agreed to "raise your children Jewish," think again.
I have a folder of emails from intermarried people whose lives turned to horror when they (or their spouses) turned back to religion. Finally, you will need to provide a positive reason in the addition to all these negatives.
That's simply the default choice in our predominantly non-Jewish society.) But imagine if the child becomes a committed Jew or Christian. If he becomes a believing Christian, he'll think the Jewish parent is going to hell for denying the faith!
And if he turns to Judaism, he'll regard him as a traitor for having intermarried! People who do not profess a belief in any particular religion often turn back to religion later in life.
In this video, a Jewish woman says: "Our marriage was going smoothly until the birth of our baby boy.
I was thrilled and wanted to arrange for a Mohel to do the circumcision. He said, 'I won't allow that bloody, barbaric cult ritual!