A father might give his son a car, freely and unconditionally, but his son’s acceptance of that gift automatically binds him to the law of the land. So, it is with Christ's free and unconditional gift of salvation, the acceptance of which automatically binds us to the law of God.
The apostle Paul said "I, therefore, a prisoner for the Lord, urge you to walk in a manner worthy of the calling to which you are called, (2) with all humility and gentleness, with patience, bearing with one another in love, (3) eager to maintain unity of Spirit in the bond of peace. (Eph 4:1-3 ESV) So that ye might walk worthy of the Lord unto all pleasing, being fruitful in every good work, and increase in the knowledge of God." (Col 1:10)
Our acceptance of Christ's gift means living each day for Him, putting off the old man and putting on the new (Eph. 4:17-32). We have privileges and duties in the local church (Acts 2:42 cf; 14:23; 20:7). If we should stumble, we can repent of our error, confess a wrong, and pray for forgiveness (Acts 8:13-24 cf; 19:17-20 f; 1 Jn. 1:5-2:2). Otherwise, we believe for nothing. (1Co15:2 ERV) We will live however if we stand fast in the Lord. (1Th 3:8 KJV)
The consequences of returning to our old godless life are beyond contemplation. Jesus said, “If anyone does not abide in me, he is thrown away like a branch and withers; and the branches are gathered, thrown into the fire, and burned. John 15:6 ESV
Out of all those who left Egypt, only two entered the promised land. God transferred his irrevocable grace to others and today Gentiles are the beneficiaries. We must ensure God does not transfer his irrevocable grace from us, to others.