From the Ligonier Ministries blog, by R C Sproul:
If It Be Your Will
When we come before God, we must remember two simple facts—who He is and who we are. We must remember that we’re talking to the King, the Sovereign One, the Creator, but we are only creatures. If we will keep those facts in mind, we will pray politely. We will say, “By Your leave,” “As You wish,” “If You please,” and so on. That’s the way we go before God. To say that it is a manifestation of unbelief or a weakness of faith to say to God “if it be Your will” is to slander the very Lord of the Lord’s Prayer.
Read the rest of the article here.