The Evils Of Catholicism
Although never stated as a fact, the evils of Catholicism is implied strongly throughout this speech. By stating that she as a Protestant has been protected by God from her enemies Elizabeth is stating that God has protected her, a Protestant, from the threat of invading Catholics, implicit in this argument the premise that God favors the Protestants.
She also makes clear that invasion from enemies would also come from a catholic country, primarily Spain. Throughout the 1500s and 1600s, the Spaniards aggressively conquered many non-Catholic nations and converted the people to Catholicism under threat of death. Phillip II was a constant threat to Elizabeth's throne and his primary objective was to extend the Catholic empire throughout Europe. By telling her troops about this threat the Queen again emphasized that the Catholics were invaders and tyrants.
Lastly, mentioning potential treachery also emphasizes the evils of Catholicism as the internal treachery came from the Scottish Plantagnets who were Catholics and intent upon taking the throne back from the Protestant incumbent.
Elizabeth's Strength As. Leader
One of the themes the Queen returns to again and again in this speech is her own readiness to fight alongside her troops if necessary. Broaching the subject of her gender as a factor that might instill concern in her subjects she assures them that she is stronger than any male monarch would be and not only prepared and able to lead from afar but also to go to battle with them. By promising to be ready to "lay down for my God, and for my kingdom, and my people..." She is emphasizing her own readiness to die alongside them.
She also continues to this theme by repeating her pledge to take up arms, showing that she is a leader from the battlefield not just on paper.