Mysticism:
Mysticism seeks for emotional experience after emotional experience. Mysticism is the idol of dynamic experiences of God rather than growing in God. It does not take advantage of all that Christ is nor does it consistently take one deeper into the glories of Calvary but it seeks temporal blasts of emotional experience. This is not to say that biblical faith is not emotionally charged nor experiencial. However, as we are Spirit indwelt, as we feed on the Word of Christ, change often takes place in the little moments of life. Faith and repentance are exercised in these little moments. 'The danger of mysticism is that is can become more a pursut of experience than a pursuit of Christ.' Pursue Christ!
Activism:
Activism seeks to defend and promote what is right. Activism is the idol of righteous living rather than a joyful pursuit of Christ. Often times activism is the fighting off of external evils at the expense of the internal evils. You will see these individuals in the picketing lines or finding and promoting new material that raves against the political, social, or even religious ills of the day. However, 'when you believe that the evil outside you is greater than the evil inside you, a heartfelt pursuit of Christ will be replaced by a zealous fighting of the evil around you.' Celebration in the Christian life is marked by the relief of social ills rather than the transforming grace of God. Hence the Gospel is reduced to a participation in Christian causes.
adapted from How People Change