I had no trouble looking up the words "faithful" or "faithfulness" in Scripture. That's because the terms are all over the place - Old Testament and New. Most of the time, the word was used to describe God.
And he passed in front of Moses, proclaiming, "The LORD, the LORD, the compassionate and gracious God, slow to anger, abounding in love and faithfulness... (Exodus 34:6 NIV)
When Moses met with God on top of Mt. Sinai, he chiseled out the two stone tablets. That's when the LORD passed in front of him and described Himself to Moses. Yahweh's own self-description is that He is "abounding in love and faithfulness."
Surely his salvation is near those who fear him, that his glory may dwell in our land. Love and faithfulness meet together; righteousness and peace kiss each other. Faithfulness springs forth from the earth, and righteousness looks down from heaven. (Psalms 85:9-11 NIV)
Love and faithfulness are often tied together when describing God. That's really good for us, because many of the gods of the other people groups of that time were either mean-spirited, aloof, or unpredictable. God, however, has a one-two punch to eliminate fear. He loves you. He is faithful. Our God, Yahweh, the LORD, is worthy of our trust because God is full of love and faithfulness.
Your love, LORD, reaches to the heavens, your faithfulness to the skies. (Psalms 36:5 NIV)
I don't know about you, but I need that reminder many times. When I face problems in life that are much bigger than me, I find myself wanting to grab control. I want to do things to fix the problems. I can even lose sight of God. Then I remember God's love, God's promises, and God's faithfulness. I start thinking about all the times God has "come through" in the past, providing what I needed right when it was needed. My faith strengthens and my resolve moves me forward. God is good all the time and all the time God is good. Not only that, God is faithful.
I will praise you with the harp for your faithfulness, my God; I will sing praise to you with the lyre, Holy One of Israel. My lips will shout for joy when I sing praise to you-- I whom you have delivered. (Psalms 71:22-23 NIV)
How about you? Do you see God's faithfulness in your life? Does it help you trust God in the difficult times?