Acts 4:12
Children have limits, that their parents do not. When we are children, this does not always seem fair. We sometimes try to tell our parents that they cannot do something because we cannot. Of course, they remind us that we are not in charge. They make the rules. It becomes even more confusing when there are more children in the family. One cannot cross the street by himself, but his older brother gets to drive where he wants to go. The parents decide which rules and limits apply to which individual children, not the other way around. The same is true in the relationship between God and humanity.
God gave the children of Israel a messiah name Jesus. They rejected him and crucified him. Their action told God that his choice for Jesus to be their savior was not acceptable to them. They wanted someone who would meet their requirements and their expectations.
Peter told them that they had no chance of dictating to God. God had made his decision, they could accept it, or they would remain separated from God. No matter how hard they looked, they would never find anyone else who could save them. Some believed, and accepted Jesus as savior. Many more continued to reject Jesus and looked for salvation elsewhere. A few years later, many Jews followed militant leaders into a rebellion against Rome; death and destruction was the result.
God is still God. His decision still stands to this day. Once we encounter the testimony about Jesus, like the children of Israel, we have no other options for salvation. We can accept Him or we can reject Him, but we will never find anyone who can replace Him. Once we know the name of Jesus, His is the only name that we can call upon to save us.
God has put upon us that limit; He has not limited Himself. The Old Testament righteous never knew Jesus, but according to scripture, God saved them. God is not limited; He always saves the righteous.