Elijah is divided into two parts. The first part relates to the prophet Elijah causing a draught in Israel because its people have forsaken the Lord and followed instead, under the rule of King Ahab, the fallen Baal. Elijah performs the miracle of raising the widow's son from the dead and then challenge the prophets of Baal to a contest to determine who is the true God. When Elijah is victorious he sentences the evil prophets to death. The second part is concerned with the efforts of Elijah's enemies to kill him, the protection afforded him by God and finally his ascension to heaven in a fiery chariot.

The oratorio Elijah is not less dramatic than any opera, although Mendelssohn himself has written no operas and his other major dramatic works include the oratorio Paulus or many scores for theatrical plays the most famous of which is Shakespeare's A Midsummer Night's Dream. We learn from Mendelssohn himself how important the dramatic was to him. He wrote to pastor Julius Schubering, his librettist, saying that: "I consider the dramatic element as the most important one... I would like it to be prominent, designed with vitality and clarity."

In 1847 Mendelssohn returned to London, his tenth and final visit there, to conduct four performances of the work. After the second evening the composer was handed a dedication from Prince Albert, the husband of Queen Victoria: "To the Noble Artist who, surrounded by the Baal worship of debased art, has been able by his genius and science to preserve faithfully like another Elijah the worship of True Art and once more to accustom our ears, amid the whirl of empty frivolous sounds, to the pure tones of sympathetic feeling and legitimate harmony, to the greet Master who makes us conscious of the unity of his conception through the whole maze of his creation from the soft whispering to the mighty raging of the elements. Inscribed in graceful remembrance by Albert."

This was no doubt a most touching and sincere gratitude to the composer who while writing the piece saw his Elijah as "a real prophet through and through, of the kind we could really do with today, strong zealous and yes even bad tempered, angry and brooding- in contrast to the riff raff, whether of the court or of the people, and indeed at odds with almost the whole world -- and yet borne aloft as if on angel's wings." That was the Elijah Mendelssohn was dreaming of, this was the Elijah he gave us.