Biblical Christianity, as practiced by the individual, is inherently mystical. And just so we're on the same page, let me define "mystical" as I am using it in this context. Mystical means that something is experienced, rather than merely known, but which does not have a seen or necessarily understandable genesis or impetus. By that definition, common aspects of Christianity are readily seen as mystical: conviction, faith, call, inspiration, grace all fit the bill.
Take a look at some passages of the Bible:
1 Corinthians 2:10-15
1 Corinthians 12:1-13
Galatians 5:4-6; 16-25
Anyone who truly believes that Jesus is the Son of God is by definition a mystic. Anyone who believes that they are born again is a mystic. Anyone who believes that God's Spirit enables them to do anything is a mystic. Anyone who believes that they experience the presence of God and have companionship with him is a mystic. Anyone practicing in real life what the Bible describes as life in Christ is a mystic.
Embrace the mystical foundation of Christianity. Christianity cannot be reduced to writing on paper, or even stone. It's written on the heart by God--it is inherently mystical. Do yourself a favor and let your inner mystic out.