I remember the first time I took my friend rock climbing with me. He was climbing up the side of this cliff and got about half way up before he reached the tricky spot. He had ascended to a nice solid ledge, but he couldn’t stay there. If he wanted to make it to the top, he would have to lean his weight off the ledge and reach blindly around the jagged corner that was sticking out of the cliff. On the far side of that edge was a nice big hold for him to grab with his hand. He wouldn’t be able to see it; he would just have to reach out and feel for it.

My friend froze.

I could see from the bottom that his legs were shaking. He didn’t believe he could lean out that far. He didn’t believe the hold was there. He didn’t believe the rope would hold him if he fell. So he didn’t even try. He let go of the rock, looked down at me, and asked me to lower him back down.

In that moment, my friend experienced the relationship between faith and belief. Acting in faith requires belief or, to put it another way, we only trust what we know. My friend didn’t believe that hold was there, so he didn’t reach for it. He didn’t believe, so he didn’t act in faith. The Christian life is reaching for the hold because we believe Christ is enough to hold us up. We are trusting what we know about Jesus and acting accordingly.

Hebrews 11 is a running record of people who put their trust in God. Verses 17-19 say this about Abraham: “By faith Abraham, when he was tested, offered up Isaac, and he who had received the promises was in the act of offering up his only son, of whom it was said, ‘Through Isaac shall your offspring be named.’ He considered that God was able to even raise him from the dead, from which, figuratively speaking, he did receive him back.”

The author of Hebrews here is remembering the events of Genesis 22. How could Abraham listen to God at the risk of losing his son? Wouldn’t the promises be void? Wouldn’t that make God cruel? Abraham went up that mountain because he believed. He believed what God said about himself. Abraham knew he wouldn’t ultimately lose his son because God is true to his promises. He went out in faith because he believed that God could even raise the dead.

What do you believe about Jesus? Who is he to you? Only when we know who Jesus truly is – and believe him – will we ever trust him in faith.