5:20 Now then, we are ambassadors for Christ, as though God were pleading through us: we implore you on Christ’s behalf, be reconciled to God. 21 For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him.
An ambassador is an official envoy, especially a highest ranking diplomat who represents a state and is usually accredited to another sovereign state, or to an international organization as the resident representative of their own government or sovereign or appointed for a special and often temporary diplomatic assignment.
You see there are two kingdoms: God's kingdom and the dominion of Satan. At the present time Satan's kingdom is confined to this world. We are the only beings in the entire universe or multiverse that he has access to. The messages from his side are many, conflicting, and confusing because as Jesus pointed out, he is a liar and the father of all lying. He has convinced some that we came from random chance in a universe that has no meaning. Stuff happens. When we die it's over. As such you best eat, drink, and be merry for tomorrow you die. He has convinced others that death is an illusion and no one ever dies, they just enter a new dimension, a different phase. Some he has convinced there is no God. Others are convinced there is a God but He is not to be trusted. Others he has convinced that there are many gods etc... Still others he has convinced that we are all gods.
Confusion. That is the essence of his kingdom.
What we know for certain in this life is that something is very wrong, not just around us, but in us. We do things we wish we didn't do. We don't do things we wish we did do. We say things we don't want to say and struggle to say the things we wish we could. It's like we are prisoners within our own selves.
Then someone tells us about Jesus. We hear the Story and piece by piece the confusion clears away. We are prisoners. We have two kingdoms within our own mind. One desires to give and receive love, the other desires to be selfish. The selfish side has done some stuff that has caused others pain, and us shame, and guilt. When we find out about Jesus we discover that burden of guilt and shame and the fear that comes with it has long ago been dealt with. We discover we can leave the kingdom of selfishness and darkness and fully enter the kingdom of love and light. When we do we become ambassadors of the King. We become His representatives in a world still fumbling in confusion and darkness. We have the privilege of turning the light on in the minds of others.
God has long ago reconciled us to Himself through Jesus. All that's left is for us to understand that and embrace it and then we become reconciled to Him. It's sort of like being penniless and then finding out we have money that was given to us through an inheritance long ago and it's just been sitting in an account until we could be found and notified. Jesus provided the inheritance of forgiveness full and free. It's our job as Christians to let people know it's there, waiting for them to claim it.
And you though being a Christian was difficult and complicated... It is not at all complicated but it is difficult because we are ambassadors in hostile territory but we have nothing to fear because He that is in us is greater than he that is in the world. :)