Faith is being sure of what we hope for and certain in what we do not see. Scientific facts rest on evidence. Our human senses grasp the evidence and we come to believe that fact. Faith goes a step further.
I think it is safe to say that there is always a “leap” to believe in anything. A risk is involved. There are consequences in being wrong. When presented with God’s Word and the truth regarding salvation only through Jesus Christ, there is a tremendous eternal risk of rejecting God’s invitation. It’s like someone standing outside your house yelling, “Fire!” You can believe the messenger by weighing the evidences around you (i.e. smell smoke, see flames) or choose to ignore the person’s message. You can believe them and run the risk of running outside if its all a joke, or choose not to believe and risk being burned up. If you choose to suspend judgment, you risk the same thing. There is no such thing as a “risk free” position.
The most reasonable thing to do is believe. The evidence for Christianity is strong and worth consideration. The alternatives are comparably weak. Plus, the risk of not believing is far greater than the risk of believing. If Christianity is false, you’ve lost nothing. If it’s true, you’ve lost all eternity.
Christianity is relationship-oriented. Jesus Christ wants to introduce himself to you in the Gospels and desires for you to know him. He already knows and loves you and He desires for you to love him. When one becomes a Christian and begins to cultivate a relationship with Jesus Christ, the certainty of faith increases as well. Christ becomes a living reality. A person knows Him not only on the basis of the evidence, but on the basis of an experiential relationship. Christ is living in them. So, the question is ultimately not how can you risk believing in Christ, but how you can risk otherwise.