8.1 How do we know that Jesus Christ will come back to the earth?
ANSWER:
(a) Because God promised it in the Old Testament.
See Psalm 110:1-2; Daniel 7:13-14.
(b) Because the Lord Jesus promised his disciples that he would return. See Matthew 16:27; Revelation 22:12.
(c) Because the angels of God said so. See Acts 1:11.
(d) Because the Apostles taught it.
See Acts 3:20-21; 1 Thessalonians 4:16.

8.2 When will he come?
ANSWER:
At God's appointed time; in the near future. See Acts 17:31; Romans 2:6,16.

8.3 How do we know this?
ANSWER:
Read Luke 21:24-27 and see how the signs of the return of Jesus are being fulfilled today. The Jews have returned to the land of Israel, and Jerusalem is no longer under the rule of Gentiles. (Verse 24). There is trouble, fear and wickedness in the world on a massive scale. (Verses 25-26). Unless Jesus comes soon, men will completely destroy themselves.
See also Matthew 24:36-41; 2 Timothy 3:1-4; Ezekiel 37:21-28. Note:
A hundred years ago there was no nation of Israel. The land of Israel was then a Turkish colony. Many Arabs lived there, but only a few thousand Jews. Today, Israel is a strong nation, with nearly three million Jewish inhabitants. This is a very clear sign that the Kingdom of God is near.
See Jeremiah 30:3, 21-22, 24; Ezekiel 36:24-28; Ezekiel 37:21-28.