That's pretty much how this worked. You kept throwing down truths until they finally worked their way in and started to grow on their own. Verity couldn't convince him. But she could keep supporting him until he managed to convince himself.

"Let's say you and I do have kids," she said quietly. "And I decide that their whole existence is for the sole purpose of defeating the Covenant. That's the whole reason I give birth to them: they have to take down the Covenant brick by brick. Even ignoring how unhealthy and unfair it is for me to put that all on them...could you really look at the child in your arms and believe that they have no value beyond that purpose? That if they die in the attempt, they don't deserve to be brought back because they failed?"