In the readings today, Isaiah tells King Ahaz what should be joyous tidings: that the Lord bids him to ask for a sign. Why does the king refuse? His words, 'I will not put the Lord to the test,' are humble enough on the face of it, but Isaiah instead conveys vexation? How should the king have responded? I guess he should have responded graciously. God is a magnanimous giver of gifts. Whether by insincerity, or by false humility, or even by pride, the king's refusal seems not to be the right answer.
In the Gospel reading from Luke, the angel Gabriel announces to Mary that she is to be the blessed mother of the Son of God, the Word of God, Christ and king. To these tidings, our Lady responds with perplexity and some anxiety, and the angel is not offended. This was, after all, a girl of fourteen years or so, and so her response was understandable, and really quite sincere. And her ultimate response caps it off: 'I am the handmaid of the Lord, let what you have said be done to me,' or, as the more romantic translations say, 'let it be done to me according to thy word.' I like this version because that word is the Word of God, himself.
This, I think, is how we should respond when faced with God's gifts. We are called to be gifted (not just called and gifted), for the Lord delights in his creation, and his love is everlasting. To his graciousness, and it is really proper and courteous -- we should say "Thank you!" and accept the gift.