Final answer:
Constantine contributed to the widespread acceptance of Christianity through his Edict of Milan, his support of Christian institutions, and his conversion to Christianity.
Step-by-step explanation:
Constantine contributed to the widespread acceptance of Christianity through several key actions. Firstly, he issued the Edict of Milan in 313, which granted religious toleration and legal recognition to Christianity, ending the persecution of Christians. This allowed Christianity to grow and flourish within the Roman Empire. Additionally, Constantine actively supported Christian institutions and empowered Christian officials, further promoting the spread of Christianity. His conversion to Christianity and his patronage of the Church set a precedent for the position of the Christian emperor within the Church, establishing Christianity as a legitimate and influential religion.