To many people the Lord God is an unknown God. They either haven't met Him yet or they don't want to know Him. Some others think they know Him but they only know "facts and figures" about Him.
When Paul saw this altar to the unknown God, he begin to tell the people who He was. He began to make Him known. Why? Because it is God's will that we know Him. He doesn't want to remain "unknown". He wants to reveal Himself to you. He wants you to know Him. He wants you to know Him in a personal and intimate way. This is one of the reasons why He sent His Son Jesus into the world.
When Jesus came, He revealed Father/God to mankind-- when you have seen Me you have seen the Father. He made known His power to us-- He went about healing the sick, casting out devils, raising the dead. He made known His grace-- neither do I condemn you, go and sin no more. He made known His love-- by dying on the cross to save us from our sins. He made known His mercy-- I will have mercy on you. He made known His compassion to us-- when He saw the crowds, He was moved with compassion. Jesus made known the Father's provision-- He fed the 5,000 with fish and bread. Everything we needed to know about Father/God Jesus revealed. He showed us everything from His great love to His tender mercies. And He let us know that it is God's will that we know Him.
Do you know Him? Is He still unknown to you? Do you want to know Him? You can. He wants you to know Him. He knows who you are and He desires that you not only know who He is, but know Him through a relationship. How do we come to that place of knowing Him? By calling out to Him and asking Him for that relationship. Accepting that it came through Jesus Christ and place your faith in Him as the way to come to know the Father.
Have a great day. The Lord wants you to know Him.