Religious practitioners who are unable to conceptualize the invincible, Nirakaar (having no form) form of God believed in Saguna Brahman, one having attributes. Those indulging in rituals always believed that God, Parmatman had a form prime reason why they all worshipped God in Idol form.
Different names of God with an attribute are Bhagwan, Ishwar, Hari, Sanatana Purusha etc.
Religious practitioners considered God as a doer and worshipped a decorated God. Believers of religion also believed in Lord Brahma, Lord Vishnu and Lord Shiva attributes of God.
For commoners, masses to pray to God simply image did not work. They idolized God. Practitioners of religion believed in various attributes of Brahman, hordes of gods and goddesses. Such believers ritually went to a temple almost as a daily routine to pray to god, worship god.
Unmindful of the fact that God Almighty truly existed in miniscule form in all living beings including human form as our soul atman existing in heart, they did not desist going to temples, churches and mosques. For them God was the giver of all and also the end of the story relating to god.
The world is full of believers who believed in Saguna form of God (having attributes). The believers of Saguna form of God also believed in Sakaar Brahman (having a form). The prime reason to believe in Saguna form of God arose from dictates of ego. Our egoistic attitude failed to realize that God was Nirakaar (having no form) and also Nirguna (without an attribute).