 Your spirit is connected to the Holy Spirit. Your spirit is one with the Holy Spirit. You can't separate the two. And so in the spirit, you are mature. In the spirit, you know God. You have perfect, unhindered fellowship with Him. In the spirit, you understand His will, His ways. You have joy and peace and love and power. So when you grow spiritually, it's not really your spirit growing. Rather, it's your spirit man gaining more influence over the other aspects of your person. Like the soul and the body.