Calvinism (500 years ago) started with Augustine, 1600 years ago. Arminianism started 500 years ago. Greek Orthodox (Trinitarians) separated from the western church in 964 AD.
Calvinism
Predestination as to who is in Christ. Vast majority of people suffer eternal conscious torment. Only God can get you in Christ.
Arminianism
You get in Christ by faith plus some good works. How you get in is how you stay in. You are in by performance. Often fear based. You get yourself in Christ.
Trinitarianism
All of humanity is sovereignly included in Christ. Evangelism is getting people to wake up to their inclusion.
Before the reformation repentance after death was standard theology.