Yes, we are "fearfully and wonderfully made" (Psalm 139:14) by God in His image and likeness, (Genesis 1:26) but because we are sons and daughters from Adam's seed, we have a sin nature. As long as we're on this earth we'll be subject to sinful temptations. "The heart is deceitful above all things, and desperately wicked," the Bible says in Jeremiah 17:9.
Many of the Founding Fathers, and perhaps most of them, made a regular practice of reading the Bible from cover to cover every year. They really knew and applied God's truth to all of life, including the government they were putting together from the individual states. Recognizing the Biblical truth that man is sinful and must not be entrusted with unrestrained power, our wise ancestors divided the power of the national government into three parts or three different branches with different duties. Each part was given some authority by the people for carrying out their respective responsibilites for the people. All of the power rests in the people, individuals subject to the God who created them. We delegate some of our power to the legislative branch, to make just laws to protect our God-given freedom. We delegate somewhat less of our power to the executive branch, to carry out and enforce those just laws, made by our lawmakers, representing you and me. Lastly, we delegate even less of our power to the judicial branch, to settle disputes between states, etc. To make sure the bounderies between the branches are respected, with no branch of government sneaking over the fence to steal some power we did not delegate to them, (as sinful men operating government have a tendency to do,) we listed each one's duties and each one's authority, setting up road blocks for each to police the others. The division of power into three distinct parts or branches is called "Separation of Powers", and the roadblocks restricting power grabs are called "Checks and Balances." Beautiful, isn't it? And all carefully crafted to protect the freedom of the people by law, because the Founding Fathers recognized the Biblical truth that man has a sin nature. They built a unique system of government, acting on that truth, being "doers of the Word, not hearers only." James 1:22