the holy grail is Jesus if you accept his lordship you get eternal life, but the way you probably see the holy grail is as a cup which that whole thing with the knight's of the round table was a kids story to begin with but some synonyms for the holy grail might be San greal, cup of Christ, the most holy vessel, any number of things like that.

Another response:

The Holy Grail is also known as the San Graal, San Greal, Sange Réal (holy blood),

The Holy Chalice or The Cup of Christ.