I'm a Christian and I have read the Bible daily for nearly forty years.
One thing used to bother me a lot: how the Old Testament figures, especially King David, could both decry violence in what they wrote, and yet ask God's blessings upon slaughter of their enemies.
Studying gangs has illuminated this problem for me. When the Old Testament writers penned their passionate concepts, they lived in a world of gangs. A gang is a group that seeks to impose its will on other groups. A gang seeks no conflict resolution except within its own membership. Everyone else is to be defended against.
Such was the nature of the world of the Old Testament. The OT has examples of peace negotiations, but overall, the extant groups expected each other to make war. They lived knowing that at any time, a raid might occur. The winner would claim a superior God.
God's drive to bring peace among the people He created is evident in the progression throughout the Old Testament. He pointed out the consequences of treating each other badly: the Israelites drove out groups whose lives had become characterized by bloodshed and sexual immorality, and immediately God warned them that if they behaved like the vanquished people, God would allow Israel to be vanquished -- which they did and He did.
The Old Testament doesn't both encourage violence and discourage it. Instead, it describes a world in which violence was the expectation and God alone could break through that expectation with his commandments. Byt the time of the New Testament, people were ready to see Jesus, who never set one group against another, and picked up a weapon -- a whip -- only to frighten evildoers out of the Temple.
We contradict God when we justify killing others in His name. There is no other way for light to shine except by persistent peaceful resolution of conflicts. The drive to peace is what reveals the face of God.