Preheat oven to 375°F. Lightly grease a 7X 11 inch baking dish. In a medium bowl, mix together the cream cheese and mayonnaise until smooth. Mix in the artichoke hearts, spinach and Parmesan cheese. Season with garlic and lemon juice. Spread evenly into the prepared baking dish. Bake covered for 20 minutes. Remove the cover, and let the dish bake uncovered for 5-10 minutes, or until the surface in lightly browned.