If everyone who gets into heaven, gets into heaven through the mercy of God, will everyone get into heaven?
Well, the answer to that is No! Not everyone will go to heaven. The Bible says: “And these will go away into everlasting punishment” (Mt 25:46), and again, “He who believes in Him is not condemned; but he who does not believe is condemned already, because he has not believed in the name of the only begotten Son of God”. (Jn 3:18) So some will not be recipients of the mercy of God. This must mean that there are some conditions fixed to the mercy of God.
Why is God so serious about being merciful?
The mercy of God cannot be enjoyed without satisfying the justice of God.
The justice of God could not be satisfied without the death of Christ as our substitute.
So for an individual to enjoy the mercy of God, they have to acknowledge that Christ died for them. Paul wrote: “… the Son of God … loved me and gave Himself for me”, (Gal. 2:20) because –“God did set forth (Christ) a mercy seat” (Rom. 3:25) (Young’s literal & Darby)