Read a work on the "Evidences of Christianity," and it may become highly probable that Christianity, etc. , are true. This is an opinion. Feel God. Do His will, till the Absolute Imperative within you speaks as with a living voice, "Thou shalt, and thou shalt not;" and then you do not think, you know that there is a God.
. . . that is our calling: to show that there is a reality in personal relationship, and not just words about it.