The impact on the Spanish Inquisition on Christianity is more of an example when people use religion as a way to gain more political power. Unfortunately we see this same behavior, the justification of following God's will in various parts of the world, such as the problems in Nigeria and the atrocities in the Sudan.
When leaders, or political activists seek to gain power, and the ministers provide the religious backing, by stating this is God's will, then we have abuses such as in Guantanamo prisons, as American's torture and denigrate people of other religions.
But we also have some people in Europe and the US that continue to talk about killing Muslims because of their religion, when the goal is financial gain, under the cover of religion.
So, the Spanish Inquisition was a very dark period, and should never have happened, but as long as Christians idly stand by and don't stand up for those that believe differently, showing God's Love to the world by our willingness to die for those that may hate us, or those that are different than we are, we are all guilty of the atrocities committed, and even listening to ministers espouse such hatred, and saying nothing is just as bad as doing the action, as words not only damage our relationships with others, but also what we say, or listen to and say nothing, reflects on whether Christ is truly within us.
For a brief talk about the politics behind the Inquisition:
For an essay on Words healing or hurting:
Here are a couple of quotes on what we say:
Proverbs 10:18-19 (NKJV):
18Whoever hides hatred has lying lips, And whoever
spreads slander is a fool. 19In the multitude of words sin is not
lacking, But he who restrains his lips is wise.
Psalm 141:3 (NKJV):
Set a guard, O Lord, over my mouth; Keep watch over the door of my lips.