'Lamb of God' refers to the role Jesus Christ played when He was sacrificed on the cross to atone for the sins of mankind. Jesus was crucified around the time Passover lambs were being sacrificed in the temple, according to Jewish custom (John 19:14). In 1 Cor. 5:7 we read about the Last Supper "Get rid of the old yeast that you may be a new batch without yeast, as you really are. For Christ, our Passover lamb, has been sacrificed."
John the Baptist calls Jesus the Lamb of God who takes away the sins of the world (John 1:29) refering to the prophecy we can read in the Old Testament (Isa. 53:7 and Jer. 11:19) where the lamb symbolises a suffering servant.
The Lamb Cross or Agnus Dei Cross portrays a lamb marching from right to left carrying a cross. The cross is sometimes replaced by a victory flag. (See also Portate Cross)
Showing a lamb with a cross gets over the problem of attempting to reproduce a physical likeness of Jesus, as we see in a crucifix. The crucifix, showing a man wracked by pain, helps us recall the suffering Christ bore for us; the lamb helps us recall how meekly Jesus accepted his role.
A lamb is the prominent component of many church seals. Take, for example, the Moravian Church.
Moravia is a region with a fascinating history in the easternmost part of today's Czech Republic. The Moravian Church uses an Agnus Dei as their seal with the surrounding inscription Vicit agnus noster, eum sequamur (Our Lamb has conquered, let us follow him), just as sheep follow the shepherd and depend on him for protection. More than that, the sheep depend on their shepherd for survival.
The lamb has conquered; an awesome statement and well worth looking further into.
How could anyone as feeble as a lamb conquer anything, let alone conquer evil? Throughout history, Christian crusaders have sadly taken the opposite approach to conquering what they believe to be sinful. Even today, we are so passionate in believing that our ways are right, and that we have a duty to bring other people up to our standard. For their own good. And if that means violence, then so be it.
This is the antithesis of what Jesus taught and demonstrated.
Jesus taught in His 'Sermon on the Mount':
"You have heard that it was said, 'Love your neighbour and hate your enemy.' But I tell you: Love your enemies and pray for those who persecute you, that you may be sons of your Father in heaven." (Matt. 5:43-45)
Jesus didn't make any exceptions or conditions; he was quite clear about it. There's no alternative or optional version, this command is an essential part of Christianity. Acting meekly is not a spindly sign of impotence - it can be very tough to follow the clear command of Jesus Christ.
Yet we should not forget that God will not demand anything we are not capable of achieving. And God will equip us with all the armaments we need.
It's all there in Eph. 6:10-17.