Thank you for theological question, “If the angels are ministering spirits sent to serve believers, and if the spirits of the prophets are greater than any prophet was on earth, would Mary in Heaven not also be greater than she was on earth?”
The Scriptures affirm that angels are servants of God with the function to serve those who will inherit salvation. Hebrews 1:14 says this, “Are not all angels ministering spirits sent to serve those who will inherit salvation?” (A searchable online Bible in over 150 versions and 50 languages). Bible citations are from the New International Version. Furthermore angles are stronger than humans since they do not have physical limitations.
The second part of one’s statement is incorrect. Angels are messengers from God but they are not viewed as being spirits of the prophets. The one who gives the message to the prophets is the Holy Spirit. II Peter 1 says this, “20 But know this first of all, that no prophecy of Scripture is a matter of one’s own interpretation, 21 for no prophecy was ever made by an act of human will, but men moved by the Holy Spirit spoke from God.” In other words, the words of the Old Testament prophets and the New Testament writers were guided by the Holy Spirit, not the angels. At times, angels carried the message to humans as to Lot or Mary, but they didn’t speak on their own accord or authority.
The third part of the statement of Mary in heaven is greater than Mary when she was on earth in my opinion is also faulty. It would seem that her faith and willingness to be the means whereby the Son of God would be born through her by the Holy Spirit is more highly honored on earth than in heaven. She took a step of faith and obedience even though she didn’t fully understand how that was going to happen to her. In heaven, she is honored and commended for her obedience on earth. The commendations or rewards that believers will receive is for their works of faith on earth. Each believer will receive their own reward. I Corinthians 3 says this, “According to the grace of God which was given to me, like a wise master builder I laid a foundation, and another is building on it. But each man must be careful how he builds on it. 11 For no man can lay a foundation other than the one which is laid, which is Jesus Christ. 12 Now if any man builds on the foundation with gold, silver, [d]precious stones, wood, hay, straw, 13 each man’s work will become evident; for the day will show it because it is to be revealed with fire, and the fire itself will test [e]the quality of each man’s work. 14 If any man’s work which he has built on it remains, he will receive a reward. 15 If any man’s work is burned up, he will suffer loss; but he himself will be saved, yet so as through fire” (NIV).
Does Mary have an honored place in heaven? Yes, but she is not the only one for the the Scriptures record in Hebrews 11 of the Heroes of the Faith. If the question relates to the “exaltation” of Mary over all the other believers as being “The Mother of God”, that designation should be the mother of Jesus just as Elizabeth was the mother of John the Baptist. Every believer has the same access to our Heavenly Father since we are all children of God on earth and upon our death those believers will rest from all their works and enjoy the presence of God.
SUMMARY: Angels and humans are servants of God with each being given a function to do for God on earth.
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