Eph 1:13-14 teach about how one is placed "in Christ":
13 And you also were included in Christ when you heard the message of truth, the gospel of your salvation. When you believed, you were marked in him with a seal, the promised Holy Spirit,
14 who is a deposit guaranteeing our inheritance until the redemption of those who are God’s possession—to the praise of his glory.
Additionally, Eph 4:30 clarifies one of the results of being in union with Christ:
30And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption.
Paul even reiterates this point twice in 2 Cor;
1:22 - set his seal of ownership on us, and put his Spirit in our hearts as a deposit, guaranteeing what is to come.
5:5 - Now the one who has fashioned us for this very purpose is God, who has given us the Spirit as a deposit, guaranteeing what is to come.
Further, consider Rom 6:5 - For if we have been united with him in a death like his, we will certainly also be united with him in a resurrection like his.
Then v.8 - Now if we died with Christ, we believe that we will also live with him.
All of these verses are promises for those who have been placed in union with Christ as a result of believing in Him, per Eph 1:13.
None of these verses have any conditions for these promises for those who are "in Christ".
Some have claimed that certain sins, or more sins, or unrepentant sins will sever this union in Christ, which seems incredulous given the certainty of these promises.
However, note Ro 5:20 - The law was brought in so that the trespass might increase. But where sin increased, grace increased all the more,
So, what is one result of being "in Him"?
1. Living with Him, per Rom 6:8
2. guaranteeing what is to come (salvation, obviously, or the day of redemption, per Eph 4:30)
3. united with Him in resurrection, per Rom 6:5
4. guaranteeing the redemption of those who are God's possession, per Eph 1:14
What do all of these things refer to? All who believe are sealed with the Holy Spirit, which is a guarantee of God's possession for the day of redemption.
Therefore, all who have believed will be redeemed, based on being "in Christ".
13 And you also were included in Christ when you heard the message of truth, the gospel of your salvation. When you believed, you were marked in him with a seal, the promised Holy Spirit,
14 who is a deposit guaranteeing our inheritance until the redemption of those who are God’s possession—to the praise of his glory.
Additionally, Eph 4:30 clarifies one of the results of being in union with Christ:
30And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption.
Paul even reiterates this point twice in 2 Cor;
1:22 - set his seal of ownership on us, and put his Spirit in our hearts as a deposit, guaranteeing what is to come.
5:5 - Now the one who has fashioned us for this very purpose is God, who has given us the Spirit as a deposit, guaranteeing what is to come.
Further, consider Rom 6:5 - For if we have been united with him in a death like his, we will certainly also be united with him in a resurrection like his.
Then v.8 - Now if we died with Christ, we believe that we will also live with him.
All of these verses are promises for those who have been placed in union with Christ as a result of believing in Him, per Eph 1:13.
None of these verses have any conditions for these promises for those who are "in Christ".
Some have claimed that certain sins, or more sins, or unrepentant sins will sever this union in Christ, which seems incredulous given the certainty of these promises.
However, note Ro 5:20 - The law was brought in so that the trespass might increase. But where sin increased, grace increased all the more,
So, what is one result of being "in Him"?
1. Living with Him, per Rom 6:8
2. guaranteeing what is to come (salvation, obviously, or the day of redemption, per Eph 4:30)
3. united with Him in resurrection, per Rom 6:5
4. guaranteeing the redemption of those who are God's possession, per Eph 1:14
What do all of these things refer to? All who believe are sealed with the Holy Spirit, which is a guarantee of God's possession for the day of redemption.
Therefore, all who have believed will be redeemed, based on being "in Christ".