Today's Gospel reading indicates that there are demons, even in the synagogue or in church. Demons surround us. We usually can't get away from them. Moreover, they are very active in trying to deceive, confuse, tempt, manipulate, seduce, control, depress, harass, hurt, destroy, and damn us. Under these circumstances, we must know how to prevent the evil one from touching us (see 1 Jn 5:18).
Only by giving our lives to Jesus do we have the Holy Spirit through which we have protection from and victory over evil spirits. When we are living our Baptisms, we are rejecting Satan, his works, and his promises. We conquer Satan and his demons by obedience to the Lord (see 2 Cor 10:4-6; Rm 16:19-20). If we have sinned and been defeated by the evil one, we can recover by repentance, especially as expressed through the Sacrament of Reconciliation. We condemn ourselves to live with some demons and their destructive activities, unless we take God's word seriously and receive the Lord's victory through prayer and fasting (Mt 17:21, NAB).
The presence of demons need not disrupt our lives. If we fully live our Baptism in the Father, the Son, and the Holy Spirit, we will grow holy and rule in the midst of our demonic enemies (Ps 110:2).