When two people get together to do business, they make a contract. Both people make a promise to help each other so that both of them benefit. However, if one of those people breaks his promise, then the other person is allowed to break his promise, too. For example, a waiter at a restaurant promises to give customers food; in turn, the customer promises to pay the waiter money. However, if the customer refuses to pay, then the waiter is not obligated to bring out any food, and vice versa.
Promises that God makes aren't like promises people make, though. Unfortunately, people sometimes break promises, but God never breaks His. God doesn't make contracts like people do. God makes covenants. That's a promise made out of love, an unconditional promise, a one-sided promise. It means that even if one person breaks his promise, the other person will still keep up his end of the deal. It means that even when we disobey and fall to sin and give God every right to hate us, He still doesn't abandon us, because He promised, “I will not leave you nor forsake you” (Joshua 1:5). Whatever we do, good or bad, God is always good. When we are faithless, He is faithful. Even when we mess up and fall short, He can be trusted to remain perfect.
The gospel message is, in and of itself, one of God's promises. In the Old Testament, people had to perform lots of rituals and give up lots of sacrifices in order to pay off their sins. They needed a priest to talk to God for them, because they could not themselves. When God sent Jesus to die on the cross for us, though, He promised that Jesus' sacrifice was enough. He promised we would not have to do anything to try to earn His love. He already loves us so much! Jesus also promised that we would receive the Holy Spirit, so we could have access to God and hear from Him without needing a priest to act as a middle man. No matter how badly we fail, Jesus is enough to forgive us; we just need to turn from our sin and toward Him.
Hebrews 10:23 says, “Let us hold fast the confession of our hope without wavering, for He who promised is faithful.” What do we hold fast to, exactly? How do we know what to look forward to or what we can trust in? Where can we find God's promises?
Simple, really. God put it all in one convenient place: the Bible. The words God has spoken are full of His promises! This new rule of not needing animal sacrifices is a new promise from God. It's called the new covenant, or the New Testament. The more we spend time reading the Word and learning from it, the more we'll understand who God is and what He offers.