How do we know that faith and doubt can coexist?

This coexistence of faith and doubt is illustrated in the story of Peter walking on water. When Peter stepped out in faith, he initially succeeded, but as he began to focus on the waves, doubt crept in, and he started to sink. Jesus did not rebuke Peter for doubting but highlighted that even 'little faith' was still faith. This phenomenon occurs because believers experience the tension between their spirit, which is renewed by God, and their flesh, which remains weak and susceptible to doubt. It is a natural part of the Christian walk, where faith is sometimes overshadowed by doubt due to our limited understanding and earthly circumstances.