Thats a symbolic verse, and notice that it says "Kingdom of Heaven" vs "Kingdom of God".
Notice that when Jesus is talking about the KOHeaven, He says to "repent, because its at hand".
However, when He's talking about the KOG, He says.....>"the KOG is within you".
So, one is dealing with Jesus on the Earth as the KOHeaven come down, and one is describing the spiritual kingdom that lives inside the Believer, who has become "the temple of the Holy Spirit".
The KOHeaven struggle, is symbolic of the struggle between darkness and Light, is one safe teaching.
What it does not mean is that if you fight to go to heaven using your willpower and self effort, then you'll make it.
I don't think it is symbolic christians are called to suffer with and for our savior!
Matthew 10:38
And he that taketh not his cross, and followeth after me, is not worthy of me.
Matthew 16:24
Then said Jesus unto his disciples, If any man will come after me, let him deny himself, and take up his cross, and follow me.
Matthew 7:14
Because strait is the gate, and narrow is the way, which leadeth unto life...
1 Peter 4:16
Yet if any man suffer as a Christian, let him not be ashamed; but let him glorify God on this behalf.
2 cor 4:17 For our light affliction, which is but for a moment, worketh for us a far more exceeding and eternal weight of glory;
2 cor 5:15 And that he died for all, that they which live should not henceforth live unto themselves, but unto him which died for them, and rose again.
2 Thessalonians 1:5
Which is a manifest token of the righteous judgment of God, that ye may be counted worthy of the kingdom of God, for which ye also suffer:
Colossians 1:11
Strengthened with all might, according to his glorious power, unto all patience and longsuffering with joyfulness;
2 Tim 2:3
Thou therefore endure hardness, as a good soldier of Jesus Christ.
Phil 1:29
For unto you it is given in the behalf of Christ, not only to believe on him, but also to suffer for his sake;
2 tim 1:8
Be not thou therefore ashamed of the testimony of our Lord, nor of me his prisoner: but be thou partaker of the afflictions of the gospel according to the power of God;
1 Peter 5:10
But the God of all grace, who hath called us unto his eternal glory by Christ Jesus, after that ye have suffered a while, make you perfect, stablish, strengthen, settle you.
Hebrews 10:36
For ye have need of patience, that, after ye have done they will of God, ye might receive the promise.
James 1:3
Knowing this, that the trying of your faith worketh patience.
James 1:4
But let patience have her perfect work, that ye may be perfect and entire, wanting nothing.
thks