I believe there are two realities in salvation. There is the positional reality where we are positionally placed in Christ the moment we believe. This is apart from any behavior change or even water baptism. The second salvation reality is experiential. For one to experience the reality of salvation in their life one must live according to the will of God. This includes water baptism. Each step we take in obedience to the faith will bring us into a more deeper and life changing experience of God's saving work in us. It's these experiences that change us to become more like Christ.