In Hebrews 3:1 It talks about brothers in Christ partaking of the heavenly calling.And in Mark 3:35.Jesus says who ever does the will of God is my brother.But how can people be partaking of the heavenly calling?If only 144,000 go to heaven?
First... none really "go to heaven" -they inherit the earth -and then the entire creation.
As for the 144,000, they are simply those who are called specifically to serve God at a specific time.
Just after those servants are mentioned, many more are mentioned as being saved out of the tribulation -of every people....
9After this I beheld, and,
lo, a great multitude, which no man could number, of all nations, and kindreds, and people, and tongues,
stood before the throne, and before the Lamb, clothed with white robes, and palms in their hands;
10And cried with a loud voice, saying, Salvation to our God which sitteth upon the throne, and unto the Lamb.
11And all the angels stood round about the throne, and
about the elders and the four beasts, and fell before the throne on their faces, and worshipped God,
12Saying, Amen: Blessing, and glory, and wisdom, and thanksgiving, and honour, and power, and might,
be unto our God for ever and ever. Amen.
13And one of the elders answered, saying unto me,
What are these which are arrayed in white robes? and whence came they? 14And I said unto him, Sir, thou knowest. And he said to me, These are they which came out of great tribulation, and have washed their robes, and made them white in the blood of the Lamb.
15Therefore are they before the throne of God, and serve him day and night in his temple: and he that sitteth on the throne shall dwell among them.
16They shall hunger no more, neither thirst any more; neither shall the sun light on them, nor any heat. 17For the Lamb which is in the midst of the throne shall feed them, and shall lead them unto living fountains of waters: and
God shall wipe away all tears from their eyes.