When we speak of inheritance it means to receive something for which we did not work and of which we did nothing to deserve it… It also implies that someone else paid for it and that this person died for bequeath us his legacy. The inheritance Paul is talking about in this verse is the one that Christ bequeathed to us, it is His inheritance… Christ died so that we could be reconciled to the Father and receive life in abundance. We haven't done nothing to deserve it, that's called grace. What is extraordinary is that Christ was resurrected, death could not hold him back (cf. Acts 2:24). So we have the inheritance while still having the relationship with Christ, isn't that amazing?
However, we must fight for His legacy. It is not a fight against other people, but first of all against ourselves and against spiritual powers (cf. Ephesians 6:12) in order to be able to live according to His inheritance. In Ephesians 1:18 Paul says he is praying that our eyes will be opened so that we know the glorious riches of His inheritance. His heritage is life in abundance and we must fight against any small and narrow mentality in our lives that prevents us from believing in His abundance (cf. Ephesians 3:20). God has given everything for us and we have everything fully in Christ (cf. Colossians 2:10), there is no limit… So it is up to us to fight in prayer to live our lives as disciples to the measure of His Heritage…
In Him we have healing (1 Peter 2:24), we must fight against any spirit of sickness and infirmity that wants to reach us. We have to fight against what makes us believe that certain diseases are normal… Like for example wearing glasses, in heaven no one will wear them, which means that Christ has already healed our eyes… Too often we accept things like normal when they are not! It is up to us to fight against ourselves so that our lives remain in the reality of the Kingdom of God. Another thing, we have to fight against what wants to keep us restricted to this earthly life in order to always keep the vision of eternity. His inheritance is eternal life with Him and our whole life must be lived in this reality, which changes our relationship to many things (cf. Romans 8:18). It's up to you to determine which fights you have to fight.
However in this verse Paul tells us about the inheritance of Christ, His inheritance is that all may be saved and come to the knowledge of the truth (cf. 1 Timothy 2: 4). Here when it comes to pagans it is not negative, it simply means those who have not yet made Christ their Lord and Savior. However they are His inheritance, Christ died for them so that they could receive forgiveness, reconciliation with God and eternal life. They are called to be one body with us, His body which is the Church to enter into His promise. Our fight for His heritage is first of all here, to make His mission our priority (cf. Matthew 28:19). His heritage is the salvation of the greatest number
How to fight for this? First of all in prayer, pray that everything that prevents lives from meeting God will be overthrown, that they will be freed from the spirit of blindness that prevents them from seeing the reality of the Gospel (cf. 2 Corinthians 4: 4). We are called to pray for those with whom we rub shoulders so that their hearts can be opened for the Gospel, it is a question of blessing them. Another important thing, God wants everyone to be saved and they all share the same inheritance. Never abdicate on anyone, never say that it is not possible for such and such a person to be saved, because it is a lie… Jesus clearly says when speaking of salvation that everything is possible with God (cf. Mark 10:27 ). So let's always expect the people around us to find out about Jesus.
Ultimately it involves committing to a lifestyle where we witness to His love and presence. Where we propose to pray for the different needs, which means that we must fight against our fears, our apprehensions, etc ... To become the witnesses that He calls us to be, we have received His power to live this (cf. Acts 1: 8) and the world is just waiting for us to share the reality of the Good News of Christ (cf. Romans 8:19). So let's not wait, let's fight together for His Legacy!
God has blessed you richly so that you bless abundantly ...
Luke
English (UK) 
Français