The Bible does not specifically tell us to ask ourselves the WWJD question. Since we are flawed human beings who are still prone to sin and who are certainly not Jesus, it is dangerous to assume we would know what Jesus would do. Even while Jesus was on earth, His actions often surprised others. Rather than relying on this question, a better question to ask is this: “Is what I am wanting to do in alignment with God’s Word and a heavenly minded perspective?” This line of thought is what Jesus commends from His Sermon on the Mount (Matthew 5—7; see specifically 6:33). The Bible clearly lays out what is sin (2 Timothy 3:16-17). Anything that goes against God’s standards, we shouldn’t do. For less clear situations, we must learn to seek God’s will through wisdom, understanding, applying, and obeying the underlying principles of His Holy Word (James 1:5; 1 Corinthians 2:10–16) by the power of His Holy Spirit (Galatians 5:16–18, 22–26).
Assuming that we can answer the question, WWJD is presumptuous. Among a group of people presented with a similar situation will be different responses for what each thinks Jesus would do. Since Christ sees everything about every situation, including what we cannot see, we must ask Him what to do rather than assume it.
This is why knowing and living by God's Word is so important. The more we know what God has revealed through His word, the less time it will take to discern His will in a given situation. In especially “gray” situations that we can’t find clear answers to from His Word, we should pray to God and rely heavily on the Holy Spirit to guide us.
WWJD may initially seem like a good guide for our actions, but a much better question is, "What has Jesus said for me to do from His Word?" and praying “Father, please help lead me through your Holy Spirit to make a wise decision.” This question and prayer avoid assuming we have the answer to what Jesus would do based on our own flawed, human perspective. If we want to lead godly lives, we must truly seek Jesus' will—not assume we already know it.