What is it exactly that Jehovah’s Witnesses believe? How do we as Christians witness to them?

Jehovah’s Witnesses (JWs) trace themselves back to about 1870 and the teachings of a man named Charles Taze Russell (1852-1916). Russell, among others, felt that mainstream Christian doctrines had fallen into error, and he felt they had to be corrected. In fairness, he did not see himself as the founder of a new denomination, or himself as any kind of prophet or authority on his own behalf but, nevertheless, the beliefs he taught were grossly erroneous with the teachings of the Bible. Among their beliefs are the following: (1) There is only one God, and only person is God (the Father); he is called “Jehovah.” He has a body and is not omnipresent (everywhere present at once). He uses angels to know what is happening everywhere. The Son is one with God in purpose but not in nature; therefore he is a lesser god. The Holy Spirit is not a person but a force from the Father. That is why JWs consider the “Trinity” to be an erroneous doctrine. (2) While they do consider the Bible to be the inspired word of God, they view other translations as distortions of the truth. They only subscribe to “The New World Translation Of The Holy Scriptures (1961).” However, many Greek scholars in particular view their Bible as the one which distorts the truth, adding and/or changing words in critical places to validate their doctrinal views. For instance, while the NIV translates John 1:1 as: In the beginning was the Word, and the Word was with God, and the Word was God—John 1:1, the New World Translation states it like this: “In the beginning was the Word, and the Word was with God, and the Word was a god,” thus fitting their belief that Jesus was a lesser god and, in fact, a created being. Another example: Paul’s words to the Colossian church that: He is the image of the invisible God, the firstborn over all creation. For by him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things were created by him and for him. He is before all things, and in him all things hold together—Paul, I Colossians 1:15-17, becomes for JWs, “He is the image of the invisible God, the firstborn of all creation, because by means of him all other things were created in the heavens and upon the earth.” Again, the word “other” was inserted so that the text would reflect Christ as not eternal but rather as a created being. (3) JWs believe that Jesus is actually Michael the archangel. He existed that way before Bethlehem; while on earth Jesus was a sinless man of flesh; after the resurrection, Jesus became a spirit—Michael again. That also makes his resurrection a spirit resurrection, not a physical, bodily resurrection. (4) Humans are a soul/body identity. At death, we simply cease to exist. Hell is the grave, not a place of departed spirits. There is no place of conscious torment. At the resurrection, believers are re-created into new persons. (5) Salvation is through good works. Good works must be done to ensure inclusion in the Book of Life. They believe that 144,000 have already been selected for heaven so, for the rest of us, there will be earthly paradise. (6) All churches are distortions of the truth and therefore instruments of the devil. Only the JWs have the truth. (7) At the end of time, everyone will be resurrected to either salvation or to a second-chance trial for life. Anyone who rejects the second chance will be annihilated.
How do we witness? Pray for wisdom, and share the truth of the Scriptures with them: that God is so much more than they have been led to believe—that he is omnipotent (I know that you can do all things; no plan of yours can be thwarted—Job speaking to God, Job 42:2), omnipresent (Who can hide in secret places so that I cannot see them?” declares the Lord. “Do not I fill heaven and earth?” declares the Lord—Jeremiah 23:24), omniscient (He determines the number of the stars and calls them each by name. Great is our Lord and mighty in power; his understanding has no limit—Psalm 147:4-5) and omnibenevolent (The Lord appeared to us in the past, saying: “I have loved you with an everlasting love; I have drawn you with unfailing kindness—Jeremiah 31:3). God is not made up of a body but is an immaterial Spirit who exists eternally as Father, Son, and Holy Spirit (see Ephesians 1:3-14. And Jesus is nothing less than God Himself (But about the Son he says, “YOUR THRONE, O GOD, WILL LAST FOR EVER AND EVER, AND RIGHTEOUSNESS WILL BE THE SCEPTER OF YOUR KINGDOM. YOU HAVE LOVED RIGHTEOUSNESS AND HATED WICKEDNESS; THEREFORE GOD, YOUR GOD, HAS SET YOU ABOVE YOUR COMPANIONS BY ANOINTING YOU WITH THE OIL OF JOY”—Hebrews 1:8-9 [quoting Psalm 45:6-7]; see also John 1:1-14, 10:30-33; Colossians 1:15). A good question: How do they know they have ever done enough good works to justify inclusion in the Book of Life?