What?

It is never okay to tell a lie. God does not need our deception to accomplish His purpose. Faith is to trust Him.

However, we are living in a sinner's (forgiven) body, we will still deal with our self-will flesh to lie. There may be some circumstances, and we don't know what circumstances they might be, but there may be some circumstances where we do not necessarily have to say everything that could be said.

We will have to consider the following:
When reading Joshua 2: about Rahab's lying.

During the 50's, 60's, 70's and 80's, Christians were smuggling Bibles and books into Eastern Europe (Russia and Romania) and when a person got to the border with a load of books and Bibles and was asked point-blank, "Do you have any Bibles?" What would be our ethical answer to that?

If any of you saw Hiding Place, Corry Ten Boom’s story about hiding the Jews and lie to the Nazi soldiers.

We all should be aware of our weaknesses. We all need to understand that we all have weaknesses. Often the problem is that when we face our weaknesses, we often rely on self more than God's Grace.