Why did ancient israelites believe connecting to god?

They have this belief that God is one and is concerned with the actions of mankind. It was also proven that God manifested himself to Abraham and promise him with descendants and a nation named Canaan. It was later on proven by God's interference on the slavery done on the Israelites by the Egyptian which has led to Exodus to Canaan and the foundation of the 10 commandments. Through this occurrences it has proven that connecting to a God can save a race and a nation from intruders.