The number one things which a person must do if he really wants to find the true religion is to lay aside all pre-concieved notions of all the religions. GK Chesterton says something to that effect. Humility and openness are the keys. This does not mean they open themselves to every spirit and "god" out there. It means they examine the claims of all the founders of the religions, and critically cross-test each one against the other. Now in about 35 more days, I will tell you the biggest difference.
Are you talking about the Sacrifice of our Lord occurring in 35 more days as the big difference, Credo?
To expand somewhat on what Vandaler says: St. Thomas observes that it begins with faith. If a person believes, has faith, that there is a God, then the rest follows and is provable. Yes it requires faith first. St. Thomas observed that those lacking faith must be approached on that level. Perhaps they have to learn to see that faith is reasonable. But those whose god is Reason will have a hard time with this leap. Western society is (presently) founded upon the notion that doubt is truth, that received wisdom is unwise, that questions are the answer, that life is an experiment. Faith is contrary to these premises, and indeed many people who profess faith may actually have what amounts to a secondary faith in their religion, and a primary faith in the secular values they see around themselves.
About the secondary and primary faith part you mentioned, creimann, I have been thinking of this. How can one have two faiths? Or if one is to have two faiths, then that is simply not having one faith, and if one of those faiths is the True Faith, then that means that person does not truly have the True Faith. Simply put: the person does not believe the Truth. There is this silly separation of believing and knowing that bothers me. They say they believe in the Catholic faith, and then they go turn around and accept the possibility of or respect the faith of a false religion. What gives?
EDIT: Again, if you try believing in a synthesis of two faiths (one being the Truth), then you do not really believe the Truth because you would think that the Truth plus error totals the Truth, when that is not so. You would be believing then in a false religion altogether, for if you believe the Truth, then that is all you would need to believe. Why go and make concessions and compromises to error?