"We have faith" or "We trust"
"Hearts" here is a metonym for "thoughts and intentions." AT: "cause you to understand" (See: rc://en/ta/man/translate/figs-metonymy).
Paul speaks of God's love and Christ's endurance as if they were destinations on a path. AT: "how much God loves you and how much Christ has endured for you" (See: rc://en/ta/man/translate/figs-metaphor)