What is the sound interpretive approach to “that they increase in faith” in Qur’an 48:4?

Increase and Decrease of Faith: Assent, Conviction, and Detailed Belief

• Assume increase must always mean deeds because no other meaning is possible
• Assume numerical growth in essence without considering alternative readings
• Determine what increases through context and argument
• Reduce increase to a passing feeling without examining the context of tranquility