Christian activism can involve the political or social arena of reform; snooping into the business of others; invading the privacy of others; self-righteousness and legalism, to name a few.
This activism usually involves Christians imposing God on others, or their standards on others. The world is full of bullies who impose or enforce their beliefs on others. Activism results in arrogance when power-lust patterns dominate the soul. Many activists are well meaning and can even do good things. We must remain active for the cause of Christ and the Gospel.
Pastors especially should not be involved in activism because their full-time purpose is to study and teach — edifying the body of Christ. Pastors are not called to demonstrate or pursue political ambitions. Jesus Christ controls history and God’s Pre-designed Plan is steadfast and sure (Acts 2:23).