Without it, we can't do any good in the world. You can't truly help others with their problems. You can't find your purpose in the world. You can't talk to God. You can't hear from God. You can't receive from God. You can't receive that free gift of yours from God which involves saving your spirit from eternal damnation. Most importantly, you can't have a relationship with God.
With faith, we can do loads of good in the world. You can help set others free from their problems. You can find your purpose in the world and fulfill it. You can talk to God all you want. You can hear from God. You can receive from God. You can receive that free gift of yours from God which involves securing your seat in heaven. Most importantly, you can have a relationship with God that knows no bounds.
This faith we have in God protects us more than we know, and because of that initial 'leap' of faith, we have an awesome relationship with God to whom we can say, "Abba, Father."